bluuebunny/crossref_metadata_2025 huggingface dataset:
2D to 3D rectangular waveguide filter designs from linear iterated prediction space mapping optimization
Authors: Hinojosa Juan , Quesada Pereira Fernando D. , Alvarez‐Melcon Alejandro
Published: May 2009

In this article, an optimization procedure is described to align electromagnetic (EM) three‐dimensional (3D) models with two‐dimensional (2D) models for the design of RF/microwave circuits. The optimization procedure is realized from a modified standard space mapping (SM) approach. The mapping function between the 2D and 3D parameter spaces is directly obtained from a linear iterated prediction method, which reduces the computational cost and also avoids inverse transformations. The linear iterated prediction 2D to 3D SM optimization of evanescent rectangular waveguide bandpass filters with inductive posts for the 2D models and non‐inductive posts for the 3D models illustrate the advantages and the challenges of this approach. The proposed method is simple to be implemented, it requires a reduced computational cost and it can be useful for CAD environment with 2D and 3D circuit structure electromagnetic (EM) analysis. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1979–1983, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24459
RF performance assessment of AlGaN/GaN MISHFET at high temperatures for improved power and pinch‐off characteristics
Authors: Aggarwal Ruchika , Agrawal Anju , Gupta Mridula , Gupta R. S.
Published: May 2009

An investigation of temperature model for an AlGaN/GaN MISHFET is presented and a relative comparison is done with conventional HFET structures. The proposed analytical model demonstrates its inherent ability to operate at higher temperature. The contributions from various temperature dependent material parameters are taken into account alongwith the effect of temperature on the sheet carrier concentration and threshold voltage of the device. The model is further extended to predict the temperature dependence of transconductance, cut off frequency and pinch‐off characteristics. The investigated temperature range is from 25°C–300°C. Non linear Fermi potential (Ef) variation with the sheet carrier concentration (ns), and the highly dominant effects of spontaneous and piezoelectric polarization at the AlGaN/GaN heterointerface are also considered. AlGaN/GaN MISHFETs demonstrate larger drain currents, cut‐off frequency and better pinch‐off characteristics at high temperatures. The model is based on closed form expression and does not involve elaborate computation. The analytical results on the transport characteristics of both the devices are compared with available experimental data and are in good agreement. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1942–1949, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24461
Compact planar monopole antenna for 3G and UWB applications
Authors: Nabil Srifi Mohamed , Krishna Palukuru Vamsi , Essaaidi Mohamed , Jantunen Heli
Published: May 2009

This article presents a compact printed monopole antenna for 3G and UWB mobile and wireless communication systems. The antenna consists on printed microstrip arms on a Rogers' substrate with a slotted partial ground plane. The size of the antenna is only 16 mm × 36 mm × 0.83 mm. The simulated and measured results show very good agreement. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1939–1942, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24462
A new broadband hybrid bow‐tie antenna for wireless applications
Authors: Sun Jwo‐Shiun , Hu Chih‐Kai , Lee Yi‐Chieh
Published: May 2009

The main goal of this letter is to increase the impedance bandwidth of a hybrid bow‐tie antenna with end‐fire radiation pattern by combining with slots and a patch radiator. The proposed antenna simplify the structure of an antenna with the merits of light weight, low cost, ease fabrication for many wireless and mobile applications. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1905–1908, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24463
Transmission and reflection properties of composite metamaterials in free space: Experiments and simulations
Authors: Li Minhua , Yang Helin , Wen Ding‐e
Published: May 2009

Free‐space microwave measurements are applied on composite metamaterials (CMMs) consisting of split ring resonators (SRRs) and wires, also known as left‐handed material. Our experiments are based on a type of CMMs with unique configurations and the transmission and reflection measurements performed in free space exhibit a pass band at about 9 GHz. Simulation results are also given, which are in good agreements with experiments. The widely belief of the pass band is that the stop bands of the SRRs alone and the wires alone constitute a clear demonstration of left‐handed (LH) behavior. The LH behavior only take place in the medium with simultaneously negative permittivity ε, and permeability μ, also called double negative materials. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1865–1868, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24465
A robust method for locating the poles of Green′s function in lossless or lossy multilayered media
Authors: Chen R. S. , Zhuang W. , Wang D. X. , Ding D. Z.
Published: May 2009

This article describes a robust method for locating the poles of the spectral‐domain Green's functions in a lossless or lossy multilayered medium. Real‐coded genetic algorithm (RGA) is first introduced to approximate the locations of the surface‐ and/or leaky‐wave poles and then followed by a Cauchy's integral theorem to rapidly refine the poles and remove the unwanted ones. Numerical examples demonstrate the accuracy and efficiency of the method. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1929–1934, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24472
A reconfigurable multiband patch antenna for wireless applications using MEMS switches
Authors: Zhang Chunna , Yang Songnan , Pan Helen K. , Fathy Aly E. , El‐Ghazaly Samir , Nair Vijay K.
Published: May 2009

A compact multiband antenna has been redesigned to be reconfigurable with embedded switches to allow selective addressing of these bands. The concept, simulation, and implementation of developing these reconfigurable antennas using MEMS switches and their relevant experimental demonstrations will be discussed in this article. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1892–1896, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24474
Low‐loss and high‐isolation active type cascode switch in 0.13‐μm CMOS for millimeter‐wave applications
Authors: Lee Dong Ho
Published: May 2009

This article presents two types of switches which are fabricated in 0.13‐μm standard CMOS process characterized up to 50 GHz. The first is the conventional series NMOS switch with an optimum gate width which is adjusted by measuring various sized devices. The second is a new active type cascode switch for millimeter‐wave phased array systems. The series NMOS switch produces 3 dB insertion loss and 7.5 dB isolation at 40 GHz. In contrast, the active type cascode switch has 7.5 dB better insertion loss (Gain) and 20 dB better isolation than the passive switch at 40 GHz. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1856–1858, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24476
Comments on “Higher order Inhomogeneous Impedance Boundary Conditions for Perfectly Conducting Objects”
Authors: Tezel Necmi Serkan
Published: May 2009

© 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2001–2002, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24477
Interpolation scheme for fast calculation of reaction terms in the characteristic basis function method
Authors: Laviada Jaime , Mittra R. , Pino Marcos R. , Las‐Heras Fernando
Published: May 2009

This article presents an acceleration technique for the fast calculation of the impedance matrix elements in the method of moments in the case of using characteristic basis functions (CBFs). This technique is based on taking advantage of the smooth amplitude and phase behaviors of the fields generated by a CBF when the distance is sufficiently large. Computational efficiency is realized by calculating the reaction between a source‐CBF and a test‐CBF by first evaluating a sampling of the field at a sparse set of points, and then computing the fields at the rest via the use of interpolation. Thus, this procedure avoids the highly expensive integration in the source domain that is needed to calculate the radiated field in the entire test domain when following the conventional procedure. Phase unwrap prior to interpolation and the fast sample calculation scheme are detailed in the article. The technique has been validated by considering several examples involving Radar Cross Section computations. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1818–1824, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24478
Filtering applications of a novel cylindrical dielectric core inhomogeneous MTL provided with a sliding conducting ring
Authors: Brandão Faria J. A.
Published: May 2009

A novel inhomogeneous MTL device consisting of a solid cylindrical dielectric core with four equidistant cylindrical thin wires running along the core's peripheral surface, parallel to the core axis, is examined here from the standpoint of its filtering properties. At the input port of the MTL device three adjacent conductors are bonded together, whereas at the output port the same three conductors are loaded with 50 Ω resistors. For tuning purposes, a conducting ring is made to longitudinally slide along the MTL structure in contact with the MTL wires. Frequency‐domain transfer functions for the output voltages are determined as a function of the sliding ring position. Computed results show that the proposed structure exhibits noticeable selectivity features, controlled by the ring position, which can be used advantageously for filtering applications. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1815–1818, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24479
An X‐band microstrip oscillator integrated with frequency‐selecting patch antenna
Authors: Lee D. H.
Published: May 2009

A simple design for microstrip oscillator consisting of an active source and an output patch antenna is presented. The active source is designed to possess negative‐resistance over broad bandwidth but not to oscillate without the output patch antenna. Two different source circuits that are potentially unstable over full C‐band and X‐band are fabricated. Six different‐size patch antennas are then connected with each source circuit to demonstrate the oscillation frequency control. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1963–1966, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24481
Design and analysis of an ultrawideband three‐section microstrip‐slot coupler
Authors: Seman Norhudah , Bialkowski Marek E.
Published: May 2009

This article presents the design of a three‐section microstrip‐slot coupler aimed for operation in the frequency band between 3.1 and 10.6 GHz. The coupler's design is accomplished in a two‐layer dielectric substrate and consists of rectangular sections of microstrip lines that are broadside coupled by a slot in the common ground plane supporting the two substrates. The initial dimensions are worked out using simple formulas. Next, CST Microwave Studio simulator is applied to carry out the final design. The designed coupler is manufactured and its performance is tested. The tests show a good performance over an ultra wide frequency band range from 3.1 to 10.6 GHz. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1889–1892, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24484
Subwavelength metamaterial‐based resonant cavities fed by multiple sources for high directivity
Authors: Burokur Shah Nawaz , Yahiaoui Riad , de Lustrac André
Published: May 2009

The analysis and design of subwavelength metamaterial‐based resonant cavity antennas are presented. The antennas under investigation are formed by embedding a feeding source in a Fabry‐Perot (FP) cavity composed of a Perfect Electrical Conductor (PEC) surface and a metasurface reflector. The embedded feeding source used in this study is a 2 × 2 microstrip patch array. The influence of the interelement spacing of the patch array feed on the radiation patterns is investigated and reported. The effect of the cavity thickness is also considered. Finally, the design of highly directive subwavelength cavity antennas is presented. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1883–1888, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24485
Compact 2.4/5‐GHz dual‐band annular‐ring slot antenna with circular polarization
Authors: Ren Wang
Published: May 2009

This article presents a compact dual‐band circularly polarized annular‐ring slot antenna for 2.4/5‐GHz WLAN applications. The radiating elements consist of two concentric annular‐ring slots cut on the center of the ground plane, operating at 2.4‐ and 5‐GHz bands, respectively. A pair of rectangle notches is placed between two annular‐ring slots to guarantee that the antenna can operate well at high band. The antenna is fed by a 50 ohm microstrip at the top and the substrate material is FR‐4. It has a compact size (40 mm × 40 mm × 1.6 mm) and can be integrated easily with other RF front‐end circuits in WLAN operations. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1848–1852, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24487
Broadband double‐balanced diode mixer using a Marchand balun with vertical coupling structure
Authors: Nam Hee , Lee Myeong‐Gil , Yun Tae‐Soon , Lee Jong‐Chul
Published: May 2009

In this article, a broadband double‐balanced mixer is presented using a wideband Marchand balun implementation by vertical coupler. Frequency is selected as 1.0–3.7 GHz for radio frequency (RF), 1.14–3.84 GHz for LO, and 140 MHz for IF signals. When LO signal with 7 dBm at 2.64 GHz is injected, a conversion loss of 7.5 dB, and RF to LO isolation of −45 dB are obtained. Also, an average conversion loss of 9 dB, and RF to LO isolation of −25 dB are obtained for frequency band of 1.0–3.7 GHz. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1811–1814, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24488
Temperature‐dependent transmittance of cascaded long‐period fiber gratings for sensor applications
Authors: Sakata Hajime , Honda Kotaro
Published: May 2009

We propose cascaded long‐period fiber gratings (LPFGs), whose synthesized rejection band alters in bandwidth and loss according to ambient temperature. By using an edge‐emitting light‐emitting diode as an input light source, temperature dependence of the optical power through the cascaded LPFGs exhibits either a positive or a negative temperature coefficient. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1809–1811, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24489
Quadrature cross‐coupled VCO implemented with body injection‐locked frequency dividers
Authors: Jang Sheng‐Lyang , Liu Cheng‐Chen , Huang Shin‐Hsin , Juang Miin‐Horng
Published: May 2009

This article presents a CMOS quadrature voltage‐controlled oscillator (QVCO). The LC‐tank QVCO consists of two cross‐couplednMOS divide‐by‐2 injection‐locked frequency divider (ILFDs) with a tail transistor, which serves the role of frequency doubler. The output of the tail transistor in one ILFD is injected to the bodies of thenMOSFETs in the other ILFD. The proposed CMOS QVCO has been implemented with the TSMC 0.18 μm CMOS technology and the die area is 0.595 × 0.896 mm2. At the supply voltage of 0.6 V, the total power consumption is 2.4 mW. The free‐running frequency of QVCO is tunable from 5.44 to 5.8 GHz as the tuning voltage is varied from 0.0 to 0.6 V. The measured phase noise at 1 MHz frequency offset is −115.62 dBc/Hz at the oscillation frequency of 5.44 GHz and the figure of merit (FOM) of the proposed QVCO is −186.6 dBc/Hz. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1918–1921, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24495
Performance analysis of a Radio over Fiber system based on IEEE 802.15.4 standard in a real optical network
Authors: Cerqueira Sodré Arismar , e Silva D. C. Valente , Fortes M. A. Q. R. , da Silva L. F. , Branquinho O. C. , Abbade M. L. F.
Published: May 2009

We report on an implementation of a Radio over Fiber system based on IEEE 802.15.4 standard in a geographically distributed optical network. The system performance was analyzed under real conditions of temperature, pressure, humidity, and wind. Experimental results show no signal degradation and indicate frame error rates two orders of magnitude below the typical levels of wireless sensor networks, for distances up to 160 km. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1876–1879, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24497
Implementation of a quadrature hybrid for miniature mixer application
Authors: Lai Yu‐Ann , Su Chun‐Chi , Hou Jian‐An , Lin Chih‐Ming , Wang Yeong‐Her
Published: May 2009

A quadrature hybrid using high‐pass and low‐pass lumped elements without via‐hole structure for single balanced mixer application is presented. The proposed hybrid, different from those of conventional quadrature hybrid applications, can provide not only compact size but also DC block function which is very suitable for MMIC design. Application to the mixer is presented. The best conversion loss of 5.1 dB at 37 GHz and a conversion loss greater than 11 dB for wide IF bandwidth from DC to 10 GHz can be achieved. When compared with the conventional single balanced mixers, more than 50% area reduction can be obtained. The chip core area of the mixer is as small as 0.48 mm2. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1843–1845, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24499
A wideband aperture‐coupled microstrip antenna for S and C bands
Authors: Ghassemi N. , Rashed‐Mohassel J. , Mohanna Sh. , Moradi Gh.
Published: May 2009

This article presents a multilayer aperture‐coupled microstrip antenna with a nonsymmetric U‐shaped feed line. The antenna structure consists of a rectangular patch which is excited through two slots on the ground plane. Experimental results show that the antenna has VSWR < 2 from 2.6 to 6.8 GHz (89%) and the gain of the structure is >7 dB from 2.7 to 4.5 GHz (50%). © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1807–1809, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24500
Miniaturization of frequency selective surfaces using fractal Koch curves
Authors: Campos A. L. P. S. , de Oliveira E. E. C. , Silva P. H. F.
Published: May 2009

This article presents a proposal for frequency‐selective surfaces (FSSs) miniaturization. The FSSs are made up of a 2D periodic array of metallic Koch fractal element. The FSS prototypes were designed using the software Ansoft DesignTM and several prototypes were built. The FSS were built on a RT‐Duroid 3010 substrate. All the built FSS obtained a good agreement with simulated results. We obtained a reduction of up to 50% of area with the use of fractal Koch curves. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1983–1986, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24503
Low‐phase noise VCO using output matching network based on novel harmonic control circuit
Authors: Choi Jaewon , Seo Chulhun
Published: May 2009

In this article, a novel voltage‐controlled oscillator (VCO) using the output matching network based on the novel harmonic control circuit is presented for reducing the phase noise without the reduction of the frequency tuning range. The phase noise suppression is achieved by the harmonic control circuit having the short impedances for the second‐ and third‐harmonic components. The high‐Q resonator has been used for reducing the phase noise but has the problem that the frequency tuning range has been also reduced by the increase of the Q value of the resonator. However, the frequency tuning range of the proposed VCO has not been reduced because the phase noise has been reduced without the high‐Q resonator. The microstrip square open loop multiple split ring resonator has been used with the proposed harmonic control circuit for better phase noise property. The phase noise of this VCO has been −127.5 to −126.33 dBc/Hz @ 100 kHz in the tuning range, 5.744–5.865 GHz. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1838–1842, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24510
Optical extinction ratio monitoring techniques using optical spectrum analysis
Authors: Yang Chun‐Liang
Published: May 2009

An optical extinction ratio monitoring technique for wavelength‐division‐multiplexed passive optical network systems is proposed. This technique is based on the optical spectrum analysis. It can accurately measure the optical extinction ratio of optical signals and does not change with the transmission distance. In our experiments, the transient chirp hardly affects the measured results if the optical extinction ratio is lower than 7 dB, and the measured errors are less than 0.5 dB. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1800–1803, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24512
Compact parallel coupled‐line bandpass filter with wide bandwidth and suppression of spurious
Authors: Chin Kuo‐Sheng , Chen Yi‐Ping , Lin Ken‐Min , Chiang Yi‐Chyun
Published: May 2009

The re‐entrant coupling structure is applied in a parallel‐coupled microstrip filter design to ensure a wide bandwidth, compactness, and the suppression of spurious. Fan design graphs are provided to determine the dimensions of each coupled stage. The features and advantages of the proposed circuit are analyzed in detail. Two experimental filters with design bandwidths of 70 and 90% are fabricated to verify the effectiveness of the modified structure. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1795–1800, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24513
Das Mehr an Leittechnik
Authors: Krämer Stefan
Published: May 2009

Zur Prozessführung gehören nicht nur das Prozessleitsystem, sondern auch die technischen Maßnahmen der Leit‐und Regelungstechnik sowie die Produktionsmannschaft.
Gestaltung von Partikeln — Produktdesign disperser Stoffe
Authors: Rähse Wilhelm
Published: May 2009

Die Größe, Form, Stabilität, Rieselfähigkeit, Löslichkeit und das chemische Verhalten von Teilchen in Pulvern und Granulaten lassen sich einstellen. Enzym‐, Dünger‐ und Kunststoffgranulate, Percarbonat, Zitronensäure, Blähton, Eisenerzpellets sowie Tabletten sind Beispiele dafür.
1H NMR metabolomics study of age profiling in children
Authors: Gu Haiwei , Pan Zhengzheng , Xi Bowei , Hainline Bryan E. , Shanaiah Narasimhamurthy , Asiago Vincent , Gowda G. A. Nagana , Raftery Daniel
Published: May 2009

Metabolic profiling of urine provides a fingerprint of personalized endogenous metabolite markers that correlate to a number of factors such as gender, disease, diet, toxicity, medication, and age. It is important to study these factors individually, if possible to unravel their unique contributions. In this study, age‐related metabolic changes in children of age 12 years and below were analyzed by 1H NMR spectroscopy of urine. The effect of age on the urinary metabolite profile was observed as a distinct age‐dependent clustering even from the unsupervised principal component analysis. Further analysis, using partial least squares with orthogonal signal correction regression with respect to age, resulted in the identification of an age‐related metabolic profile. Metabolites that correlated with age included creatinine, creatine, glycine, betaine/TMAO, citrate, succinate, and acetone. Although creatinine increased with age, all the other metabolites decreased. These results may be potentially useful in assessing the biological age (as opposed to chronological) of young humans as well as in providing a deeper understanding of the confounding factors in the application of metabolomics. Copyright © 2009 John Wiley & Sons, Ltd.
Single echo acquisition MRI using RF encoding
Authors: Wright Steven M. , McDougall Mary Preston
Published: May 2009

Encoding of spatial information in magnetic resonance imaging is conventionally accomplished by using magnetic field gradients. During gradient encoding, the position ink‐space is determined by a time‐integral of the gradient field, resulting in a limitation in imaging speed due to either gradient power or secondary effects such as peripheral nerve stimulation. Partial encoding of spatial information through the sensitivity patterns of an array of coils, known as parallel imaging, is widely used to accelerate the imaging, and is complementary to gradient encoding. This paper describes the one‐dimensional limit of parallel imaging in which all spatial localization in one dimension is performed through encoding by the radiofrequency (RF) coil. Using a one‐dimensional array of long and narrow parallel elements to localize the image information in one direction, an entire image is obtained from a single line ofk‐space, avoiding rapid or repeated manipulation of gradients. The technique, called single echo acquisition (SEA) imaging, is described, along with the need for a phase compensation gradient pulse to counteract the phase variation contained in the RF coil pattern which would otherwise cause signal cancellation in each imaging voxel. Image reconstruction and resolution enhancement methods compatible with the speed of the technique are discussed. MR movies at frame rates of 125 frames per second are demonstrated, illustrating the ability to monitor the evolution of transverse magnetization to steady state during an MR experiment as well as demonstrating the ability to image rapid motion. Because this technique, like all RF encoding approaches, relies on the inherent spatially varying pattern of the coil and is not a time‐integral, it should enable new applications for MRI that were previously inaccessible due to speed constraints, and should be of interest as an approach to extending the limits of detection in MR imaging. Copyright © 2009 John Wiley & Sons, Ltd.
Differences between students and non‐students' willingness to donate to a charitable organisation
Authors: Pentecost Robin , Andrews Lynda
Published: May 2009

This paper reports on a comparative study of students and non‐students that investigates which psycho‐social factors influence intended donation behaviour within a single organisation that offers multiple forms of donation activity. Additionally, the study examines which media channels are more important to encourage donation. A self‐administered survey instrument was used and a sample of 776 respondents recruited. Logistic regressions and a Chow test were used to determine statistically significant differences between the groups. For donating money, importance of charity and attitude towards charity influence students, whereas only importance of need significantly influences non‐students. For donating time, no significant influences were found for non‐students, however, importance of charity and attitude towards charity were significant for students. Importance of need was significant for both students and non‐students for donating goods, with importance of charity also significant for students. Telephone and television channels were important for both groups. However, Internet, email and short messaging services were more important for students, providing opportunities to enhance this group's perceptions of the importance of the charity, and the importance of the need, which ultimately impacts on their attitudes towards the charity. These differences highlight the importance of charities focussing on those motivations and attitudes that are important to a particular target segment and communicating through appropriate media channels for these segments.

Copyright © 2009 John Wiley & Sons, Ltd.
Thermal and catalytic aspects of Ln(III) polymer–metal complexes
Authors: Patel Mihir M , Kapadia Malav A , Joshi Jayantilal D
Published: May 2009

BACKGROUND: In this era, polymer‐supported catalysts are gaining more attention, as they are effective in reduction of pollution, production cost and give good yield. Due to the versatility of lanthanide catalysts in organic synthesis, we envisioned that lanthanides(III) supported polymers would afford a novel type of solid phase Lewis acids.

RESULTS: The polymer–metal complexes are found to be efficient and effective catalysts in the Biginelli three‐component, one‐pot synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones. The synthesized polymer is thermally more stable and porous in nature than polychelates.

CONCLUSION: The polymer–metal complexes can be used as economical and eco‐friendly catalysts for synthesis of substituted 3,4‐dihydropyrimidin‐2(1H)‐ones with different aromatic aldehydes and β‐ketoesters. Thermal stability of the polymer is higher than that of polychelates due to the presence of intramolecular hydrogen bonding. Copyright © 2009 Society of Chemical Industry
Microstructure formation in polymer composites prepared with polypropylene and a polyaniline complex
Authors: Ríos‐Soberanis Carlos R , Ley‐Bonilla Rafael A , Cruz‐Estrada Ricardo H , Cupul‐Manzano Carlos V , Rangel‐Rodríguez Luis M , Caballero‐Can Alejandra
Published: May 2009

BACKGROUND: Results of a feasibility study to produce elongated structures of an electro‐conductive polyaniline complex (PANICOM) within polymer composites by means of an in situ deformation process are reported. The aim was to find an alternative route to produce fiber‐like polymer materials with potential applications in electrostatic discharge (ESD) protection. PANICOM–polypropylene blends with PANICOM contents ranging from 1 to 50 wt% were capillary extruded. The microstructure was analyzed using optical and scanning electron microscopy. Conductivity measurements were carried out. Tensile mechanical properties were also characterized.

RESULTS: PANICOM was deformed into elongated structures, embedded within the polypropylene, preferentially oriented in the extrusion direction. The highest conductivity levels were reached for PANICOM contents of 15 wt% and greater. For contents of PANICOM of about 5 to 10 wt%, the conductivities lay within the optimal ESD range, and the breaking tenacity was only about 25% lower than that of pure polypropylene.

CONCLUSION: The results obtained provide further evidence to support the feasibility of producing electrically conductive fibers of PANICOM within a suitable polymer matrix by means of a simple in situ deformation process, so as to allow the fabrication of conducting composites with potential applications in ESD protection. Copyright © 2009 Society of Chemical Industry
Thermal degradation behaviour of multi‐walled carbon nanotube‐reinforced poly(L‐lactide) nanocomposites
Authors: Kim Hun‐Sik , Chae Yun Seok , Kwon Ha Il , Yoon Jin‐San
Published: May 2009

BACKGROUND: Polymer/multi‐walled carbon nanotube (MWCNT) composites are one of the most promising alternatives to conventional polymer composites filled with micrometre‐sized fillers. This approach can also be applied for the improvement of mechanical properties and thermal stability of biodegradable aliphatic polyesters, such as poly(L‐lactide) (PLLA), which have been receiving increasing attention due to environmental concerns. Thermal degradation behaviour provides useful information for the determination of the optimum processing conditions and for identification of potential applications of final products.

RESULTS: The PLLA/MWCNT composites investigated showed a higher thermal degradation peak temperature and onset temperature of degradation along with a higher amount of residue at the completion of degradation than neat PLLA. Moreover, PLLA/MWCNT composites with a greater MWCNT content showed higher activation energy of thermal degradation than those with a lower MWCNT loading, which confirmed the positive effect of MWCNT incorporation on the enhancement of PLLA thermal stability.

CONCLUSION: This study explored the thermal degradation behaviour of PLLA/MWCNT composites by observing the weight loss, molecular weight and mechanical properties during non‐isothermal and isothermal degradation. The incorporation of MWCNTs into the PLLA matrix enhanced considerably the mechanical properties and thermal stability. Copyright © 2009 Society of Chemical Industry
Simulation and fabrication of heterojunction silicon solar cells from numerical computer and hot‐wire CVD
Authors: Lien Shui‐Yang , Wuu Dong‐Sing
Published: May 2009

In this paper, we will present a Pc1D numerical simulation for heterojunction (HJ) silicon solar cells, and discuss their possibilities and limitations. By means of modeling and numerical computer simulation, the influence of emitter‐layer/intrinsic‐layer/crystalline‐Si heterostructures with different thickness and crystallinity on the solar cell performance is investigated and compared with hot wire chemical vapor deposition (HWCVD) experimental results. A new technique for characterization of n‐type microcrystalline silicon (n‐µc‐Si)/intrinsic amorphous silicon (i‐a‐Si)/crystalline silicon (c‐Si) heterojunction solar cells from Pc1D is developed. Results of numerical modeling as well as experimental data obtained using HWCVD onµc‐Si (n)/a‐Si (i)/c‐Si (p) heterojunction are presented. This work improves the understanding of HJ solar cells to derive arguments for design optimization. Some simulated parameters of solar cells were obtained: the best results forJsc = 39·4 mA/cm2,Voc = 0·64 V, FF = 83%, andη = 21% have been achieved. After optimizing the deposition parameters of the n‐layer and the H2pretreatment of solar cell, the single‐side HJ solar cells withJsc = 34·6 mA/cm2,Voc = 0·615 V, FF = 71%, and an efficiency of 15·2% have been achieved. The double‐side HJ solar cell withJsc = 34·8 mA/cm2,Voc = 0·645 V, FF = 73%, and an efficiency of 16·4% has been fabricated. Copyright © 2009 John Wiley & Sons, Ltd.
Family assessment in K‐12 settings: Understanding family systems to provide effective, collaborative services
Authors: Eppler Christie , Weir Sarah
Published: May 2009

Professional school counselors, school psychologists, and other professionals working in K‐12 settings have a complex job of meeting the needs of all students. Often, referral to outside counseling is necessary; however, an effective and comprehensive counseling model advocates for school mental health professionals to employ a wide variety of techniques to ensure equitable distribution of services to all students and their families. This article explores using family assessment tools to support both students' academic achievement and their families within a school context. A case study illustrates how a professional school counselor could employ and collaborate with family assessment tools to support the student, family, and school systems. © 2009 Wiley Periodicals, Inc.
Developing math automaticity using a classwide fluency building procedure for middle school students: A preliminary study
Authors: Axtell Philip K. , McCallum R. Steve , Mee Bell Sherry , Poncy Brian
Published: May 2009

To investigate the influence of an innovative math fluency intervention, 36 middle‐school students were randomly assigned to either an experimental (the Detect, Practice, Repair [DPR]) or control condition (reading intervention). After covarying pretest scores, the DPR treatment produced a significantly higher (p = .016) adjusted mean (M) math score (M = 47.53, standard deviation [SD] = 3.26) for the intervention group when compared to the control group (M = 33.31, SD = 4.39). The intervention is described so that teachers and consulting school psychologists can implement the steps for individuals or groups (e.g., in a multitiered response to intervention model). © 2009 Wiley Periodicals, Inc.
On the structure of 3‐acetylamino‐5‐methyl‐1,2,4‐oxadiazole and on the fully degenerate rearrangements (FDR) of its anion: a stimulating comparison between the results of ‘in‐silicon chemistry’ and ‘laboratory chemistry’
Authors: Mugnoli Angelo , Barone Giampaolo , Buscemi Silvestre , Lanza Camilla Zaira , Pace Andrea , Pani Marcella , Spinelli Domenico
Published: May 2009

An accurate crystal structure determination has provided evidence for a planar conformation for 3‐acetylamino‐5‐methyl‐1,2,4‐oxadiazole (5), in agreement with quantum‐mechanical calculations in the gas phase. In the crystal, a series of strong intermolecular N7H7….O9 hydrogen bonds link the amido groups of different molecules, causing the formation of infinite parallel ordered chains. The effect of the DMSO solvent on the energy and charge distribution of compound 5 and on its relevant 5− anion, involved in a fully degenerate rearrangement (FDR), has been deepened by quantum‐mechanical DFT calculations. The calculated energy barrier for the FDR increases in going from in vacuo to DMSO, in agreement with previsions based on the Hughes and Ingold rules concerning the nucleophilic substitution of an anionic reagent (the deprotonated amido group in the side chain) on a neutral substrate (the 1,2,4‐oxadiazole ring). Copyright © 2009 John Wiley & Sons, Ltd.
Discussing prognosis in an oncology setting: initial evaluation of a communication skills training module
Authors: Brown Richard , Bylund Carma L. , Eddington Julia , Gueguen Jennifer A. , Kissane David W.
Published: May 2009

Objective: Although cancer patients from Western countries have high needs for prognostic information, the frequency of such discussions in oncology consultations is variable. Prognosis is a difficult discussion area for both physicians and patients. Physician focused Communication Skills Training (CST) has been suggested as a means to aid these discussions. We developed and tested a CST module about discussing prognosis. Training consisted of didactic teaching, exemplary video and role‐play sessions. The study aim was to develop the module and evaluate the effectiveness of the training.

Method: One hundred and forty‐two clinicians from Memorial Sloan‐Kettering Cancer Center and the New York City area voluntarily participated in the training module over a two‐year period. The module was based on current literature and followed the Comskil model previously utilized for other doctor–patient CSTs. Participants completed pre and post surveys to evaluate their own confidence as well as the helpfulness of the module.

Results: Based on a retrospective pre–post measure, participants reported an increase in their confidence about discussing prognosis (t141=−9.331, p<0.001). At least 92% of participants reported their satisfaction with components of the module by either agreeing or strongly agreeing with 5/6 different statements included in their evaluation forms.

Conclusions: This short training program demonstrated success in improving physician confidence to discuss prognosis and self‐efficacy. This result, coupled with the participant's intent to utilize new skills in clinical encounters, suggests that this is a useful module. Future research will target changes in patient outcomes as a result of the physician training. Copyright © 2009 John Wiley & Sons, Ltd.
Stabilization of conformationally dynamic helices by covalently attached acyl chains
Authors: Poschner Bernhard C. , Langosch Dieter
Published: May 2009

Acylation of proteins is known to mediate membrane attachment and to influence subcellular sorting. Here, we report that acylation can stabilize secondary structure. Circular dichroism spectroscopy showed that N‐terminal attachment of acyl chains decreases the ability of an intrinsically flexible hydrophobic model peptide to refold from an α‐helical state to β‐sheet in response to changing solvent conditions. Acylation also stabilized the membrane‐embedded α‐helix. This increase of global helix stability did not result from decreased local conformational dynamics of the helix backbone as assessed by deuterium/hydrogen‐exchange experiments. We concluded that acylation can stabilize the structure of intrinsically dynamic helices and may thus prevent misfolding.
A quantitative strategy to detect changes in accessibility of protein regions to chemical modification on heterodimerization
Authors: Dreger Mathias , Leung Bo Wah , Brownlee George G. , Deng Tao
Published: May 2009

We describe a method for studying quantitative changes in accessibility of surface lysine residues of the PB1 subunit of the influenza RNA polymerase as a result of association with the PA subunit to form a PB1‐PA heterodimer. Our method combines two established methods: (i) the chemical modification of surface lysine residues of native proteins by N‐hydroxysuccinimidobiotin (NHS‐biotin) and (ii) the stable isotope labeling of amino acids in cell culture (SILAC) followed by tryptic digestion and mass spectrometry. By linking the chemical modification with the SILAC methodology for the first time, we obtain quantitative data on chemical modification allowing subtle changes in accessibility to be described. Five regions in the PB1 monomer showed altered reactivity to NHS‐biotin when compared with the [PB1‐PA] heterodimer. Mutational analysis of residues in two such regions—at K265 and K481 of PB1, which were about three‐ and twofold, respectively, less accessible to biotinylation in the PB1‐PA heterodimer compared with the PB1 monomer, demonstrated that both K265 and K481 were crucial for polymerase function. This novel assay of quantitative profiling of biotinylation patterns (Q‐POP assay) highlights likely conformational changes at important functional sites, as observed here for PB1, and may provide information on protein–protein interaction interfaces. The Q‐POP assay should be a generally applicable approach and may detect novel functional sites suitable for targeting by drugs.
Water polygons in high‐resolution protein crystal structures
Authors: Lee Jonas , Kim Sung‐Hou
Published: May 2009

We have analyzed the interstitial water (ISW) structures in 1500 protein crystal structures deposited in the Protein Data Bank that have greater than 1.5 Å resolution with less than 90% sequence similarity with each other. We observed varieties of polygonal water structures composed of three to eight water molecules. These polygons may represent the time‐ and space‐averaged structures of “stable” water oligomers present in liquid water, and their presence as well as relative population may be relevant in understanding physical properties of liquid water at a given temperature. On an average, 13% of ISWs are localized enough to be visible by X‐ray diffraction. Of those, averages of 78% are water molecules in the first water layer on the protein surface. Of the localized ISWs beyond the first layer, almost half of them form water polygons such as trigons, tetragons, as well as expected pentagons, hexagons, higher polygons, partial dodecahedrons, and disordered networks. Most of the octagons and nanogons are formed by fusion of smaller polygons. The trigons are most commonly observed. We suggest that our observation provides an experimental basis for including these water polygon structures in correlating and predicting various water properties in liquid state.
Adsorption, desorption and dissipation of metolachlor in surface and subsurface soils
Authors: Si Youbin , Takagi Kazuhiro , Iwasaki Akio , Zhou Dongmei
Published: May 2009

BACKGROUND: Variations in soil properties with depth influence retention and degradation of pesticides. Understanding how soil properties within a profile affect pesticide retention and degradation will result in more accurate prediction by simulation models of pesticide fate and potential groundwater contamination. Metolachlor is more persistent than other acetanilide herbicides in the soil environment and has the potential to leach into groundwater. Reasonably, information is needed about the dissipation and eventual fate of metolachlor in subsoils. The objectives were to evaluate the adsorption and desorption characteristics and to determine the dissipation rates of metolachlor in both surface and subsurface soil samples.

RESULTS: Adsorption of metolachlor was greater in the high‐organic‐matter surface soil than in subsoils. Lower adsorption distribution coefficient (Kads) values with increasing depth indicated less adsorption at lower depths and greater leaching potential of metolachlor after passage through the surface horizon. Desorption of metolachlor showed hysteresis, indicated by the higher adsorption slope (1/nads) compared with the desorption slope (1/ndes). Soils that adsorbed more metolachlor also desorbed less metolachlor. Metolachlor dissipation rates generally decreased with increasing soil depth. The first‐order dissipation rate was highest at the 0–50 cm depth (0.140 week−1) and lowest at the 350–425 cm depth (0.005 week−1). Degradation of the herbicide was significantly correlated with microbial activity in soils.

CONCLUSION: Metolachlor that has escaped degradation or binding to organic matter at the soil surface might leach into the subsurface soil where it will dissipate slowly and be subject to transport to groundwater. Copyright © 2009 Society of Chemical Industry
Inhibition of enteropathogenic Escherichia coli adhesion on host epithelial cells by Holarrhena antidysenterica (L.) WALL.
Authors: Kavitha D. , Niranjali S.
Published: May 2009

Bacterial adhesion is the first step in the sequence of events leading to infection. Previous data are available on the effect of Holarrhena antidysenterica on antidiarrhoeal and antibacterial action, but there is little information on the mechanism of action of the various aspects of EPEC‐induced diarrhoea, namely adherence and translocation of the effector molecule to intestinal epithelial cells. The aim of the present study was to investigate the effects of alkaloids of Holarrhena antidysenterica (AHA) on interference in the mechanism of enteropathogenic Escherichia coli (EPEC) adhesion on host epithelial cells (INT 407 and HEp2). To determine the impact of AHA on epithelial cells, cytotoxicity (LDH), adherence, apoptotic and ultrastructural studies were performed. To analyse the effect of AHA on EPEC secreted proteins, especially EspD, INT 407 monolayers were infected with EPEC and AHA‐treated EPEC, followed by immunoblotting, probed with anti EspD antisera. The maximum percentage of LDH leakage was reduced in AHA‐treated EPEC (400 µg/mL) in both cell lines. Reduced bacterial adherence was observed under light microscopy and altered apoptotic changes were visualized using propidium iodide staining in conjunction with fluorescence microscopy, in both cell lines infected with AHA‐treated EPEC and these results were confirmed with transmission electron microscope images. The suppression of type III secretory proteins (TTSPs), EspD (∼40 kDa), was detected in INT 407 cells infected with AHA‐treated EPEC. In conclusion, AHA reduces initial bacterial adhesion to intact epithelial cells and it may exert an antiadherence effect against the pathogenesis of EPEC in host epithelial cells. Thus, the investigations provide a rational basis for the treatment of EPEC‐mediated diarrhoea with AHA. Copyright © 2009 John Wiley & Sons, Ltd.