bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of raised‐cosine pulse shaping on processing gain in acousto‐optic correlators
Authors: Bazzi O. , Mohanna Y. , Khalil F. , Assaad J.
Published: March 2008

The effects of raised‐cosine filtering on the processing gain of acousto‐optic correlators (AOC) in direct‐sequence spread‐spectrum receivers are considered. For ideal AOCs, analytical expressions are derived for the full roll‐off filter characteristics. The results are given in terms of the ratio β of the code rate to the filter bandwidth. For real AOCs, results are obtained from numerical simulation and are compared to previous results obtained for other types of filters. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1558–1561, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23431
A 5.5‐GHz SiGe HBT Doherty amplifier using diode linearizer and lumped‐element hybrid coupler
Authors: Liu Haiwen , Yoshimasu Toshihiko
Published: March 2008

A 5.5‐GHz Doherty amplifier using commercial 0.35‐μm SiGe HBT technology is proposed in this article. To improve the linearity, a predistortion using diode linearizer is adopted for biasing the peak amplifier. Moreover, to realize in fully on‐chip with circuit reduction, a 90° 3‐dB hybrid coupler and quarter‐wave transmission lines are implemented by lumped‐elements. In this design, 819 μm2 HBTs are used for carried and peak amplifiers, respectively, and 26 μm2 HBT is used for linearizer. Results verify that the power gain, P1dB, and power added efficiency (PAE) of the proposed Doherty amplifier at 5.5 GHz are 8.4 dB, 31 dBm, and 30%, respectively. Also, the adjacent channel power ratio (ACPR) and the output signal's spectrum mask are given using the 54Mcps 64QAM modulated signal at 10 MHz offset. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1554–1558, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23432
A fully integrated 2.4 GHz CMOS RF transmitter for 802.15.4 ZigBee applications
Authors: Seong Eo Yun , Jin Ryu Hyun , Lee Sang‐Shin , Don Choi Kyu , Hyun Baek Dong
Published: March 2008

A fully integrated 2.4 GHz direct up conversion RF transmitter compliant with low‐power ZigBee (IEEE 802.15.4) standard is presented. The linear and gain controlled current mirror amplifier is used for up conversion mixer. It consumes 8 mA with 1.8‐V power supply. The obtained transmitter's maximum power is 4.7 dBm and the achieved EVM is 8.4% at 0.5 dBm output. The die area of transmitter is 1.4 mm × 0.9 mm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1616–1619, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23434
Circular fractal monopole antenna based on descartes circle theorem for UWB application
Authors: Naeem Khan Salman , Hu Jun , Xiong Jiang , He Sailing
Published: March 2008

An apollonian shaped ultra‐wideband circular monopole antenna based on descartes circle theorem is presented. Different self similar geometries from DCT are analyzed and optimized for UWB applications. The proposed design is slightly modified to ensure an overall smooth current distribution limited by the junction point nature of the fractal geometries. The experimental results are compared with conventional circular disk monopole and annular monopole antenna. The measured return loss of the proposed design below −10 dB is from 2.4 to over 40 GHz and its radiation pattern is omni‐directional compared with circular disk and annular antennas in most of its impedance bandwidth. Moreover due to the fractal shape, the proposed design has less weight and wind loading effect. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1605–1608, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23437
Multiway microwave planar power divider/combiner based on substrate‐integrated rectangular waveguide directional couplers
Authors: Wang Chao , Che Wenquan , Li Chao , Liu Dongtian
Published: March 2008

One kind of novel microwave planar power dividers/combiners is proposed and investigated in this article. The narrow‐side directional couplers constructed into substrate‐integrated rectangular waveguide are employed to implement the proposed multiway power divider/combiner. The design considerations of the multiway power divider/combiner are introduced. One three‐way power divider/combiner is designed and fabricated to demonstrate the validity of the proposed strategies. Good agreement between the experiments and the simulations can be observed, demonstrating 12% reflection bandwidth at −15 dB and 10% isolation bandwidth at −20 dB. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1600–1605, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23438
Automatic calibration method for phased arrays with arbitrary aperture shape
Authors: Son Seong Ho , Jeon Soon Ik , Hwang Woonbong
Published: March 2008

A simple and automatic phase calibration method is proposed for phased arrays with even conformal aperture shape. The method is based on finding the optimal phase set such that the detected power of the receiving array from a transmitting extra antenna or, by reciprocity, that of a receiving extra antenna from the transmitting array is only maximized, using a continuous genetic algorithm (GA). This method provides a much faster and almost exact solution, when compared with exhaustive search and traditional binary GA. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1590–1592, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23441
A second‐order band‐pass frequency selective surface using nonresonant subwavelength periodic structures
Authors: Behdad Nader
Published: March 2008

A new class of band‐pass frequency selective surface (FSS) with nonresonant constituting elements and sub‐wavelength unit‐cell dimensions and periodicities is presented and experimentally demonstrated. Using this technique, low profile first‐ and second‐order FSSs with reduced sensitivity to the angle of incidence for both TE and TM polarizations are designed, a prototype is fabricated and the FSS measurement results are presented and discussed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1639–1643, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23445
Printed coplanar two‐antenna element for 2.4/5 GHz WLAN operation in a MIMO system
Authors: Su Saou‐Wen , Chou Jui‐Hung , Liu Yung‐Tao
Published: March 2008

A printed coplanar two‐antenna element suited for WLAN operation in the 2.4‐ and 5‐GHz bands for dual‐module applications in a MIMO system is proposed. The two‐antenna element is comprised of one planar inverted‐F antenna (PIFA) and one monopole antenna, both printed and integrated in a coplanar configuration on a narrow dielectric substrate with the dimensions 50 mm × 11 mm. The two antennas are excited using two separate feeds with a common ground plane. By utilizing two proposed elements spaced 10‐mm apart in the lateral direction with an optimized arrangement, the four‐antenna MIMO system obtained can achieve optimal isolation between any two of the four antennas. In comparison with the conventional dual‐band antenna with a single feed, the proposed two‐antenna element allows the 2.4‐ and 5‐GHz signals to be simultaneously received or transmitted with no external switch circuit between the antenna and modules required. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1635–1638, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23540
Photorefractive properties of double‐doped Hf:Ce:LiNbO3 crystals
Authors: Zhou Wei , Wang Biao , Yuan Wei , Ling Furi , Ma Decai , Nie Yiran
Published: March 2008

In this article, the double‐doped Hf:Ce:LiNbO3 crystals were grown by the Czochralski method and its photorefractive properties were systematically studied. Samples were treated with different oxidation/reduction. The photorefractive properties of Hf:Ce:LiNbO3 crystals were investigated by the two‐beam coupling method. The results shown that the photorefractive properties of Hf:Ce:LiNbO3 crystals were improved as compared with that of Ce:LiNbO3 crystals. The oxidation/reduction treatment had great effect on the photorefractive properties and the doping mechanism was also discussed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1693–1695, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23448
Novel wideband filter with a transmission zero based on split‐ring resonator DGS
Authors: Hou Zheng‐Zheng
Published: March 2008

A wideband microstrip filter composed of split‐ring resonator DGS and lumped chip capacitor is presented in this article, which has a transmission zero at the right out‐of‐band. By using the equivalent‐circuit analysis and parameter extracting technology for the split‐ring resonator DGS, a band‐pass filter with a wide passband from 1 GHz to 2.4 GHz is fabricated and measured, making use of lumped chip capacitors and T‐shaped open‐circuit stub to achieve series and shunt capacitance, respectively. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1691–1693, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23452
The experimental study of a polarization orthogonal single‐longitudinal‐mode distributed Bragg reflector fiber laser
Authors: Jian‐Hua Luo , Bo Liu , Yu‐Wen Lan , Shu‐Zhong Yuan , Li‐Wei Wang
Published: March 2008

In this article, we reported a polarization orthogonal single‐longitudinal‐mode distributed Bragg reflector (DBR) fiber laser. The laser operated robustly in single longitudinal mode and dual polarizations with frequency difference of 976.93 MHz. This laser has simple structure as well as frequency adjustable. It can be used in a wide range of communication, sensor, and spectroscopic applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1658–1660, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23454
Application of multisection recursive convolution in 3D FETD‐FABC simulations
Authors: Cai Yong , Mias Christos
Published: March 2008

The multisection recursive convolution (MS‐RC) methodology is successfully applied to the finite element time domain floquet absorbing boundary condition modeling of doubly periodic structures. It is shown that late time instability can be delayed by improving the accuracy of RC and it can be effectively avoided by employing extrapolation. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1651–1657, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23455
32‐GHz dual‐termination coupled CPW bandpass filter on HR‐SI
Authors: Li Xi , Shi Yan‐Ling , Ding Yan‐Fang , Chen Da‐Wei , Shen Di
Published: March 2008

Bandpass filter is an important device in portable communication and other RF systems. A dual‐termination coupled coplanar waveguide (CPW) bandpass filter (BPF) has been designed by HFSS. This dual‐termination coupled structure improves the coupling capacitances between the central metal and the matching transmission lines so that the insertion loss can be reduced. The filter has been fabricated on a high resistivity silicon substrate (ρ ≥ 1000 Ω cm) with 1 μm SiO2. It has −2.16‐dB low insertion loss at peak transmission of about 32 GHz. This filter shows good s‐parameter characteristics and it is attractive for RF ICs. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1705–1706, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23464
The application of motion compensation of ISAR image for a moving target in radar target recognition
Authors: Shin Seung Yong , Myung Noh Hoon
Published: March 2008

Inverse synthetic aperture radar (ISAR) is an imaging technique which generates a two‐dimensional (2D) high resolution image of a target. In general, ISAR image is often adequate to discriminate various missiles, military aircraft, and civilian aircraft and so on. However, if the target has complicated motion such as pitching, yawing, rolling, and maneuvering, ISAR image is not enough to classify among these targets. This article presents high resolution techniques for application in motion compensation of ISAR image for a radar backscattered signal from the moving target. A simple Fourier Transform (FT) is employed to obtain ISAR image for a moving target, then the image is usually blurred. These images blurring problem can be solved with the time‐frequency transform. In this article, we compensate the translational motion using the minimum entropy method (MEM) and rotational motion using the Gabor Wavelet Transform (GWT) for a moving target. To show the performances of each technique, we use backscattered field data of the ideal point scatterers and the simulated MIG‐25 to obtain motion compensated ISAR image and display the resolution of motion compensated ISAR images. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1673–1678, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23466
A compact internal UWB antenna for wireless USB dongle application
Authors: Shin Jaewoong , Hong Seokjin , Choi Jaehoon
Published: March 2008

This article presents a compact internal ultra‐wideband antenna for wireless universal serial bus dongle application. The proposed antenna has a simple configuration and is easy to implement by bending a simple metal plate. To widen the impedance bandwidth, the proposed antenna has a vertical patch with a bevel structure and a horizontal patch with a narrow slit. The proposed antenna satisfies the 10‐dB return loss requirement over the frequency band of 2.9–10.85 GHz (7.95 GHz) and so easily covers the UWB band of 3.1–10.6 GHz. The effects of the system ground plane on the impedance matching of antenna are studied experimentally. The detailed design of the proposed antenna is described, and experimental results including radiation patterns and peak gains are presented. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1643–1646, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23468
Reducing correlated noise in fMRI data
Authors: de Zwart Jacco A. , Gelderen Peter van , Fukunaga Masaki , Duyn Jeff H.
Published: March 2008

The sensitivity of functional MRI (fMRI) in detecting neuronal activation is dependent on the relative levels of signal and noise in the time‐series data. The temporal noise level within a single voxel is generally substantially higher than the intrinsic NMR (thermal) noise, and the noise is often correlated between voxels. This work introduces and evaluates a method that allows fMRI sensitivity improvement by reduction of these correlated noise sources. The method allows model‐free estimation of the correlated noise from brain regions not activated by the functional paradigm using a short (1–2 min) reference scan. A single regressor representing this noise‐source estimate is added to the design matrix used in the data analysis. Results obtained from five volunteers show an average t‐score improvement of 11.3% and a 24.2% increase in the size of the activated area. Magn Reson Med 59:939–945, 2008. © 2008 Wiley‐Liss, Inc.
Improved image reconstruction for partial fourier gradient‐echo echo‐planar imaging (EPI)
Authors: Chen Nan‐kuei , Oshio Koichi , Panych Lawrence P.
Published: March 2008

The partial Fourier gradient‐echo echo planar imaging (EPI) technique makes it possible to acquire high‐resolution functional MRI (fMRI) data at an optimal echo time. This technique is especially important for fMRI studies at high magnetic fields, where the optimal echo time is short and may not be achieved with a full Fourier acquisition scheme. In addition, it has been shown that partial Fourier EPI provides better anatomic resolvability than full Fourier EPI. However, the partial Fourier gradient‐echo EPI may be degraded by artifacts that are not usually seen in other types of imaging. Those unique artifacts in partial Fourier gradient‐echo EPI, to our knowledge, have not yet been systematically evaluated. Here we use the k‐space energy spectrum analysis method to understand and characterize two types of partial Fourier EPI artifacts. Our studies show that Type 1 artifact, originating from k‐space energy loss, cannot be corrected with pure postprocessing, and Type 2 artifact can be eliminated with an improved reconstruction method. We propose a novel algorithm, that combines images obtained from two or more reconstruction schemes guided by k‐space energy spectrum analysis, to generate partial Fourier EPI with greatly reduced Type 2 artifact. Quality control procedures for avoiding Type 1 artifact in partial Fourier EPI are also discussed. Magn Reson Med 59:916–924, 2008. © 2008 Wiley‐Liss, Inc.
Differentiation between benign and malignant breast lesions detected by bilateral dynamic contrast‐enhanced MRI: A sensitivity and specificity study
Authors: Jansen Sanaz A. , Fan Xiaobing , Karczmar Gregory S. , Abe Hiroyuki , Schmidt Robert A. , Newstead Gillian M.
Published: March 2008

The purpose of this study was to apply an empirical mathematical model (EMM) to kinetic data acquired under a clinical protocol to determine if the sensitivity and specificity can be improved compared with qualitative BI‐RADS descriptors of kinetics. 3D DCE‐MRI data from 100 patients with 34 benign and 79 malignant lesions were selected for review under an Institutional Review Board (IRB)‐approved protocol. The sensitivity and specificity of the delayed phase classification were 91% and 18%, respectively. The EMM was able to accurately fit these curves. There was a statistically significant difference between benign and malignant lesions for several model parameters: the uptake rate, initial slope, signal enhancement ratio, and curvature at the peak enhancement (at most P = 0.04). These results demonstrated that EMM analysis provided at least the diagnostic accuracy of the kinetic classifiers described in the BI‐RADS lexicon, and offered a few key advantages. It can be used to standardize data from institutions with different dynamic protocols and can provide a more objective classification with continuous variables so that thresholds can be set to achieve desired sensitivity and specificity. This suggests that the EMM may be useful for analysis of routine clinical data. Magn Reson Med 59:747–754, 2008. © 2008 Wiley‐Liss, Inc.
Anatomically constrained reconstruction from noisy data
Authors: Haldar Justin P. , Hernando Diego , Song Sheng‐Kwei , Liang Zhi‐Pei
Published: March 2008

Noise is a major concern in many important imaging applications. To improve data signal‐to‐noise ratio (SNR), experiments often focus on collecting low‐frequencyk‐space data. This article proposes a new scheme to enable extendedk‐space sampling in these contexts. It is shown that the degradation in SNR associated with extended sampling can be effectively mitigated by using statistical modeling in concert with anatomical prior information. The method represents a significant departure from most existing anatomically constrained imaging methods, which rely on anatomical information to achieve super‐resolution. The method has the advantage that less accurate anatomical information is required relative to super‐resolution approaches. Theoretical and experimental results are provided to characterize the performance of the proposed scheme. Magn Reson Med 59:810–818, 2008. © 2008 Wiley‐Liss, Inc.
Slice‐selective images of free radicals in mice with modulated field gradient electron paramagnetic resonance (EPR) imaging
Authors: Sato‐Akaba Hideo , Abe Haruhiko , Fujii Hirotada , Hirata Hiroshi
Published: March 2008

Continuous wave (CW) electron paramagnetic resonance (EPR) imaging can be used to obtain slice‐selective images of free radicals without measuring three‐dimensional (3D) projection data. A method that incorporated a modulated magnetic field gradient (MFG) was combined with polar field gradients to select a slice in the subject noninvasively. The slice‐selective in vivo EPR imaging of triarylmethyl radicals in the heads of live mice is reported. 3D surface‐rendered images were successfully obtained from slice‐selective images. In the experiment in mice, a slice thickness of 1.8 mm was achieved. Magn Reson Med 59:885–890, 2008. © 2008 Wiley‐Liss, Inc.
Multinuclear NMR investigation of probe construction materials at 9.4T
Authors: Marjanska Malgorzata , Waks Matt , Snyder Carl J. , Vaughan J. Tommy
Published: March 2008

This work investigates probe construction materials for their signal contribution to ultrashort echo time spectroscopy and imaging. 1H, 13C, and 31P spectra were obtained at a field strength of 9.4 T for 16 materials considered for use in probe and holder design and construction. Four of the materials were found to be suited for the construction of NMR probes, housing of RF coils, and holders for in vivo experiments. Magn Reson Med 59:936–938, 2008. © 2008 Wiley‐Liss, Inc.
Fast parallel spiral chemical shift imaging at 3T using iterative SENSE reconstruction
Authors: Mayer Dirk , Kim Dong‐Hyun , Spielman Daniel M. , Bammer Roland
Published: March 2008

Spiral chemical shift imaging (CSI) is a fast CSI technique that simultaneously encodes 1D spectral and 2D spatial information. Therefore, it potentially allows one to perform a 2D‐CSI experiment in a single shot. However, for most applications, limitations on maximum gradient strength and slew rate make multiple excitations necessary in order to achieve a desired spectral bandwidth. In this work we reduce the number of spatial interleaves and, hence, the minimum total measurement time of spiral CSI by using an iterative sensitivity encoding reconstruction algorithm which utilizes complementary spatial encoding afforded by the spatially inhomogeneous sensitivity profiles of individual receiver coils. The performance of the new method was evaluated in phantom and in vivo experiments. Parallel spiral CSI produced maps of brain metabolites similar to those obtained using conventional gridding reconstruction of the fully sampled data with only a small decrease in time‐normalized signal‐to‐noise ratio and a small increase in noise for higher acceleration factors. Magn Reson Med 59:891–897, 2008. © 2008 Wiley‐Liss, Inc.
Robust H∞ control of an uncertain system via a strict bounded real output feedback controller
Authors: Petersen Ian R.
Published: March 2008

This paper presents a new approach to the robust H∞ control of an uncertain system via an output feedback controller that is both stable and has an H∞ norm strictly less than a specified value. The uncertain systems under consideration contain structured uncertainty described by integral quadratic constraints. The controller is designed to achieve absolute stabilization with a specified level of disturbance attenuation. The main result involves solving a state feedback version of the problem by solving an algebraic Riccati equation dependent on a set of scaling parameters. Then two further algebraic Riccati equations are solved, which depend on a further set of scaling parameters. The required controller is constructed from the Riccati solutions. Copyright © 2008 John Wiley & Sons, Ltd.
New ladder‐type conjugated polymer containing carbazole and fluorene units in backbone: Synthesis, optical, and electrochemistry properties
Authors: Wang Baoling , Shen Fangzhong , Lu Ping , Tang Shi , Zhang Wu , Pan Shiwei , Liu Meirong , Liu Linlin , Qiu Song , Ma Yuguang
Published: March 2008

This article describes the synthesis and characterization of a new ladder‐type poly (p‐phenylene) (LPFC) containing alkylcarbazole and dialkylfluorene units in backbone, and its optical and electrochemical properties as well as its light‐emitting device performance. LPFC shows the well‐defined structure, high molecular weights, excellent thermal stability, and good solubility in common organic solvents. And it also shows strongly blue emission (λmax = 465 nm) with quantum efficiency of 70% in solution, while its solid emission (λmax = 470 nm) is almost the same as its solution. Electrochemical studies show that the highest occupied molecular orbital (HOMO) energy levels of LPFC is up to 5.29 eV, which is significantly higher than that of LPPP without carbazole in backbone, indicating an enhanced ability of hole injection from anodes. Furthermore, the single layer light‐emitting device using LPFC as the active layer shows blue emission (λmax = 470 nm) with maximum luminescence of ∼ 2000 cd/m2 and maximum luminance efficiency of 0.43 cd/A. The attractive properties exhibited from new ladder‐type polymer establish LPFC as a good candidate for the potential application as transporting and emitting layer in polymeric light emitting diodes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3120–3127, 2008
Simultaneous reversible addition fragmentation chain transfer and ring‐opening polymerization
Authors: Le Hellaye Maude , Lefay Catherine , Davis Thomas P. , Stenzel Martina H. , Barner‐Kowollik Christopher
Published: March 2008

The simultaneous ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) and 2‐hydroxyethyl methacrylate (HEMA) polymerization via reversible addition fragmentation chain transfer (RAFT) chemistry and the possible access to graft copolymers with degradable and nondegradable segments is investigated. HEMA and ε‐CL are reacted in the presence of cyanoisopropyl dithiobenzoate (CPDB) and tin(II) 2‐ethylhexanoate (Sn(Oct)2) under typical ROP conditions (T > 100 °C) using toluene as the solvent in order to lead to the graft copolymer PHEMA‐g‐PCL. Graft copolymer formation is evidenced by a combination of size‐exclusion chromatography (SEC) and NMR analyses as well as confirmed by the hydrolysis of the PCL segments of the copolymer. With targeted copolymers containing at least 10% weight of PHEMA and relatively small PHEMA backbones (ca. 5,000–10,000 g mol−1) the copolymer grafting density is higher than 90%. The ratio of free HEMA‐PCL homopolymer produced during the “one‐step” process was found to depend on the HEMA concentration, as well as the half‐life time of the radical initiator used. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3058–3067, 2008
Synthesis of a new diglycidylic Meldrum acid derivative and study of the curing with lanthanide triflates as initiators
Authors: González Lidia , Simokaitiene Jurate , Ramis Xavier , Salla Josep Maria , Mantecón Ana , Serra Angels
Published: March 2008

A new epoxy resin derived from Meldrum acid (DGMA) was synthesized by a two steps synthetic procedure and structurally characterized by the usual spectroscopic techniques and elemental analysis. Ytterbium and lanthanum triflates were tested as cationic initiators to cure this resin and its mixtures with diglycidylether of bisphenol A (DGEBA) in several proportions. By FTIR‐ATR spectroscopy the evolution of the groups, which participate in the curing was followed. The evolution of the curing and the Tg of the materials were studied by differential scanning calorimetry and the kinetic parameters were calculated applying isoconversional procedures. Ytterbium triflate led to a quicker curing than lanthanum. The thermal stability of the materials obtained was evaluated by thermogravimetry and the higher thermal degradability of the materials containing DGMA was confirmed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3088–3097, 2008
Analysis of multiple melting behavior of spherulites comprising ring‐band shell/ringless core in polymorphic poly(butylene adipate)
Authors: Woo E. M. , Yen Kai Cheng , Wu Ming Chien
Published: March 2008

In‐depth interpretation of ring‐banded spherulitic morphology, crystals, polymorphism, and complex melting behavior in poly(1,4‐butylene adipate) (PBA) were analyzed via a procedure of designing composite core‐shell spherulites, in which two lamellar patterns (ring‐band vs. ringless) were packed by subjecting to crystallization at two‐step temperature schemes with specific temperatures and times. By heating to 52 °C and holding at that temperature for 30 min annealing, the core can be stripped off by melting, and analysis specifically on the ring‐shell portion (with the ringless core stripped by controlled melting) proves that the highest melting peak (P4 at 55–57 °C) is likely associated with melting of the ring‐band lamellae. Furthermore, the unusually complex multiple melting in PBA can be attributed to all three widely proposed mechanisms: (1) multiple types of lamellae preexisting in crystallized PBA, (2) scan/heating induced remelting/reorganization, and (3) polymorphism of dual crystal cells. In addition, this study evidently shows that the extinction rings within the ring‐banded shell, regardless of alternate edge‐on and flat‐on mechanism or alternative origins, can be of all singly α‐crystal form, either initially or upon postheating temperature‐induced transformation. Thus, the type of crystal forms (α or β) in polymorphic PBA is mainly associated with temperature of crystallization (Tc = 28 or 35 °C), and not likely with lamellar orientation (flat‐on or edge‐on). © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 892–899, 2008
Investigation of the Correlations Between Nitro Group Charges and Some Properties of Nitro Organic Compounds
Authors: Zhang Chaoyang
Published: March 2008

The so‐called nitro group charge method (NGCM) is successfully established to investigate some properties of nitro compounds including the molecular stability measured by total energy (only for isomers), the bond lengths, bond dissociation energies (BDE), and the nitrating activities, in that the method considers the molecular structure. These properties are intrinsically and especially thermodynamically consistent with each other and can be well related qualitatively and even quantitatively with nitro group charges (QNitro). The correlations between QNitro and the properties are: (1) for nitro isomers, the more negative the average QNitro, the lower the total energy and the more stable is the isomer; (2) for any separate group of nitro compounds, the more negative QNitro, the shorter the R‐nitro bond length; (3) for the bond dissociation energy, more negative QNitro corresponds to a higher BDE of the R‐nitro bond; (4) by NGCM, the conditions, the reaction rates and the occurrence ratios of products of some nitration can be predicted and compared: the more negative QNitro of the product, the easier and faster the nitration, and the higher the occurrence ratio of the corresponding product.
Trypsin entrapped in poly(diallyldimethylammonium chloride) silica sol‐gel microreactor coupled to matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Xu Xuejiao , Wang Xiaoyan , Liu Yun , Liu Baohong , Wu Huiling , Yang Pengyuan
Published: March 2008

An enzyme‐immobilized capillary microreactor for rapid protein digestion and proteomics analysis is reported. The inner surface of the fused‐silica capillary was coated with poly(diallyldimethylammonium chloride) (PDDA)‐entrapped silica sol‐gel matrix, followed by assembly of trypsin onto the PDDA‐modified surface via electrostatic adsorption. The immobilization parameters such as PDDA content in the sol‐gel matrix, trypsin concentration and pH were investigated in detail. Protein samples including β‐casein, myoglobin and cytochrome c could be effectively digested and electrophoretically separated simultaneously in such a modified capillary. Just 2.26 ng (corresponding to 0.10–0.14 picomole) of sample was sufficient for on‐line capillary electrophoresis peptide mapping. The efficiency of the digestion was further demonstrated by digestion of a human liver cytoplasm sample and 253 proteins were identified in one unique run. Copyright © 2008 John Wiley & Sons, Ltd.
Reciprocal interactions between plants and soil in an upland grassland
Authors: Markham John H. , Grime J. P. , Buckland S.
Published: March 2008

Through the production of litter, plants with different life history strategies are predicted to both affect and be affected by the properties of soil. Competitive species are expected to increase the fertility of, and have a positive growth feedback with, soil, whereas stress‐tolerant species should decrease fertility but show no growth feedback. We maintained monocultures of competitive (Lolium perenne and Agrostis capillaris) and stress‐tolerant (Festuca ovina and Nardus stricta) grasses on an unproductive grassland for six years. The Nardus soil developed significantly greater inorganic nitrogen than the Agrostis and Festuca soil, and significantly greater soil moisture content than the Festuca soil. However, there were no differences in organic matter content, phosphate or bulk density between the soil types. In a greenhouse assay, each species was grown in soil cores from the different monocultures as well as natural turf. There were significant differences in growth between plant species and soil types. As expected, L. perenne produced the greatest amount of biomass. However, plants grown on Nardus soil were twice as large and had a 21% lower root allocation than plants grown on any of the other soil types. Lolium perenne, A. capillaris and F. ovina had significant negative growth feedbacks with their own soil (−0.460, −0.821 and −0.792, respectively) and N. stricta had a significant positive feedback (0.560). This study highlights the difficulties of predicting how plant traits will affect soil properties.
Pharmacokinetics and toxicity of zonisamide in cats
Authors: Hasegawa Daisuke , Kobayashi Masanori , Kuwabara Takayuki , Ohmura Tomoyuki , Fujita Michio , Orima Hiromitsu
Published: March 2008

With the eventual goal of making zonisamide (ZNS), a relatively new antiepileptic drug, available for the treatment of epilepsy in cats, the pharmacokinetics after a single oral administration at 10 mg/kg and the toxicity after 9-week daily administration of 20 mg/kg/day of ZNS were studied in healthy cats. Pharmacokinetic parameters obtained with a single administration of ZNS at 10 mg/day were as follows: Cmax=13.1 μg/ml; Tmax=4.0 h; T1/2=33.0 h; areas under the curves (AUCs)=720.3 μg/mlh (values represent the medians). The study with daily administrations revealed that the toxicity of ZNS was comparatively low in cats, suggesting that it may be an available drug for cats. However, half of the cats that were administered 20 mg/kg/day daily showed adverse reactions such as anorexia, diarrhoea, vomiting, somnolence and locomotor ataxia.
Isotope dating of ultrapotassic magmatism in the central Chukchi region: Rb-Sr age and geochemistry of monzonites from the Linkor stock
Authors: Efremov S.V. , Kozlov V.D. , Sandimirova G.P. , Dril’ S.I.
Published: March 2008

Isotope dating of ultrapotassic magmatism in the central Chukchi region was carried out. Based on the Rb-Sr isochron age of monzonites from the Linkor stock (107±2.2. Ma) and using earlier obtained geochronological isotope data, we have estimated the time of one of the stages of ultrapotassic magmatism, 107–113 Ma. Igneous rocks of this age occur throughout the central Chikchi region, which suggests their genetic relationship with some great geodynamic event there, likely, the accretion of the Mainit island arc to the Chukchi microcontinent. The results obtained permit the reconstruction of the geologic history of the region and can be used to construct more detailed geodynamic models.
Neoproterozoic basalts of the Paleo-Asian Ocean (Kurai accretionary zone, Gorny Altai, Russia): geochemistry, petrogenesis, and geodynamics
Authors: Safonova I.Yu. , Simonov V.A. , Buslov M.M. , Ota T. , Maruyama Sh.
Published: March 2008

Late Neoproterozoic (Late Vendian) basalts of the Paleo-Asian Ocean are found as fragments incorporated in the Kurai accretionary zone, Gorny Altai, Russia. Detailed study of their geochemistry and relationships with associated sedimentary rocks allowed us to recognize three types of basalts: (1) lavas depleted in REE, Nb and Ti, compositionally similar to N-MORB and associated with thin-bedded oceanic siliceous sediments; (2) basalts of transitional compositions, and (3) basalts enriched in the above elements; basalts of types 2 and 3 are similar to Pacific intraplate basalts and are associated with carbonate “cap” sediments. The N-MORB-type basalts generated from a depleted upper-mantle source, whereas the transitional and enriched ones from a heterogeneous mantle source. Their crystallization temperatures were estimated from the experiments on homogenization of melt microinclusions hosted by clinopyroxene phenocrysts (1160–1190 °C) and from the composition of the latter (1100–1295 °C). The geological, lithological, petrological, and geochemical data show that the Kurai basalts were formed in the geodynamic settings of mid-oceanic ridges and oceanic seamounts/islands.
Composition and origin of peculiar pyropes from lherzolites: evidence for the evolution of the lithospheric mantle of the Siberian Platform
Authors: Tychkov N.S. , Pokhilenko N.P. , Kuligin S.S. , Malygina E.V.
Published: March 2008

More than 1000 pyropes from the Muza (J3) and Ivushka (D–C) (northeastern Siberian Platform, and Khorkich (Mz) (southwestern part of the platform) kimberlite pipes, alluvial deposits of the Muna-Markha area, and granular peridotites of the Udachnaya pipe have been analyzed for major and some minor elements. As a result, a group of pyropes was distinguished whose composition is not typical of the lherzolite paragenesis (LAC pyropes). They are predominant in the Muza pipe and are widespread over the world. This group is described as a separate paragenetic type. In all known cases, LAC pyropes belong to granular clinopyroxene-bearing harzburgites, and in situ conditions for this suite are typically below 50 kbar and 1000 °C. Our own and literature data suggest that LAC pyropes may appear when the magmas corresponding to the high-degree melting of the primary magma affect the depleted peridotites of the lithosphere mantle.

The character of paleogeotherm and distribution of LAC pyropes in kimberlites and secondary collectors of varying age that occur on the Siberian Platform indicate that the lithosphere mantle was considerably thinner in the northeast and the rocks characterized by LAC pyropes played an increasingly important role in this region in the period from Paleozoic to Mesozoic and that these rocks were abundant in the lithosphere mantle of the platform’s interior. These facts as well as a considerable change in the rock composition in the lithospheric mantle and in the southwestern part of the platform in the same range of time suggest that the effect of the Permian-Triassic Siberian plume on the lithospheric mantle of the platform considerably changed its composition and structure in its separate parts.
Conodont palaeothermometry of contact metamorphism in Middle Ordovician rocks from the Precordillera of western Argentina
Authors: VOLDMAN GUSTAVO G. , ALBANESI GUILLERMO L. , DO CAMPO MARGARITA
Published: March 2008

The Yerba Loca Formation (Middle–Upper Ordovician), exposed in the Western Precordillera, San Juan, Argentina, is made up of clastic–carbonate turbidites, and basic–ultrabasic rocks. It is affected by regional Siluro-Devonian very low-grade metamorphism that locally reaches greenschist facies. At Ancaucha creek, 45 conodont samples were taken from two sections that include 30 to 50 m thick sills. In order to analyse the thermal alteration patterns produced by these intrusive bodies, conodont Colour Alteration Index (CAI) is contrasted with optical petrography and X-ray diffraction analyses of clay minerals. The intrusions are dated as post-Darriwilian (Da2), as determined by conodont biostratigraphy of the host rock, which indicates theParoistodus horridusSubzone of theLenodus variabilisZone. The distribution of CAI values defines a thermal aureole of about 2.5 times intrusion thickness that prevailed over the later very low-grade metamorphism. Metasomatism at Ancaucha creek is recorded by CAI values of 4 to 7, particularly restricted to a few layers close to the intrusions, as indicated by conodont textures and rock fabric. One-dimensional thermal computer simulation conforms to empirical data indicating temperatures greater than 600 °C for the contact zone, although it points out slightly narrower thermal aureoles. The clay mineral assemblage of most of the analysed samples (chlorite, illite, smectite and I/S mixed-layers) is complex and probably derives from several superimposed processes, thus representing non-equilibrium assemblages. In turn, KI values (0.27–0.32) indicate anchizone metamorphism, in agreement with regional CAI values of 4; consequently, the occurrence of smectite and I/S probably resulted from retrograde diagenesis processes.
Outcomes for patients referred urgently with suspected head and neck cancer
Authors: Hobson J C , Malla J V , Sinha J , Kay N J , Ramamurthy L
Published: March 2008

Introduction:

The 1998 National Health Service White Paper stated that anyone suspected of having a cancer would be seen by a specialist within two weeks. The ‘trigger symptoms’ prompting such referral have been nationally agreed by the National Institute for Health and Clinical Excellence. This study aimed to quantify the diagnostic yield of urgent referrals for suspected head and neck malignancy, and to identify reasons why patients ultimately diagnosed with malignancy may not have been referred via this pathway.

Materials and methods:

All patients referred to the trust with suspected head and neck malignancy in 2005 were included in the study. Data were obtained on date of referral, date of appointment, reason for referral and which National Institute for Health and Clinical Excellence guideline heading the referral fell under, clinical findings, and final diagnosis. Concurrently, all patients in the trust with a histological diagnosis of head and neck malignancy were identified using the computer records of the pathology department.

Results:

One hundred and seventy-seven patients were referred with suspected head and neck malignancy over the one-year study period. Of these, 169 were seen within two weeks. The commonest causes of referral were hoarseness and neck lumps. Of these patients, 22 (12 per cent) were ultimately diagnosed with malignancy. During the one-year study period, 39 patients were diagnosed hospital-wide with head and neck malignancy, 17 of whom had not been referred via the urgent referral pathway. No unifying theme was identified to explain why these patients had not been referred via this pathway.

Conclusion:

In a group of patients with symptoms suggestive of head and neck malignancy, only 12 per cent were ultimately diagnosed with cancer. Of all the patients within the trust diagnosed with head and neck cancer, 44 per cent had come from outside the urgent referral pathway.
Structure in parasite component communities in wild rodents: predictability, stability, associations and interactions .... or pure randomness?
Authors: BEHNKE J. M.
Published: March 2008

Experimental data establish that interactions exist between species of intestinal helminths during concurrent infections in rodents, the strongest effects being mediated through the host's immune responses. Detecting immune-mediated relationships in wild rodent populations has been fraught with problems and published data do not support a major role for interactions in structuring helminth communities. Helminths in wild rodents show predictable patterns of seasonal, host age-dependent and spatial variation in species richness and in abundance of core species. When these are controlled for, patterns of co-infection compatible with synergistic interactions can be demonstrated. At least one of these, the positive relationship betweenHeligmosomoides polygyrusand species richness of other helminths has been demonstrated in three totally independent data-sets. Collectively, they explain only a small percentage of the variance/deviance in abundance data and at this level are unlikely to play a major role in structuring helminth communities, although they may be important in the more heavily infected wood mice. Current worm burdens underestimate the possibility that earlier interactions through the immune system have taken place, and therefore interactions may have a greater role to play than is immediately evident from current worm burdens. Longitudinal studies are proposed to resolve this issue.
An integrated pipeline for the development of novel panels of mapped microsatellite markers for Leishmania donovani complex, Leishmania braziliensis and Leishmania major
Authors: FAKHAR M. , MOTAZEDIAN M. H. , DALY D. , LOWE C. D. , KEMP S. J. , NOYES H. A.
Published: March 2008

A panel of microsatellites mapped to the Leishmania genome might make it possible to find associations between specific loci and phenotypic traits. To identify such loci, a Perl programme was written that scans the sequence of a genome and writes all loci containing microsatellites to a MySQL database. The programme was applied to the sequences of the L. braziliensis, L. infantum and L. major genomes. The database is publicly available over the internet: http://www.genomics.liv.ac.uk/tryps/resources.html ‘Microsatellite Locus Extractor’, and allows the selection of mapped microsatellites that meet user-defined criteria from a specified region of the selected genome. The website also incorporates a primer design pipeline that will design primers to amplify the selected loci. Using this pipeline 12 out of 17 primer sets designed against the L. infantum genome generated polymorphic PCR products. A tailed primer protocol was used to label all microsatellite primers with a single set of labelled primers. To avoid the culture of parasites prior to genotyping, sets of nested PCR primers were developed to amplify parasite DNA eluted from microscope slides. The limit of detection was approximately 1·6 parasite equivalents. However, only 6/56 DNA from slides stored at ambient temperature for over 6 months gave positive PCR results.
Case-control study to identify risk factors for bovine cysticercosis on farms in Switzerland
Authors: FLÜTSCH F. , HEINZMANN D. , MATHIS A. , HERTZBERG H. , STEPHAN R. , DEPLAZES P.
Published: March 2008

Taenia saginatacysticercosis causes financial losses to the beef industry and farmers, and represents a significant source for human infection in many countries. A case-control study was conducted to identify risk factors for bovine cysticercosis on farms in Switzerland. The case group (n=119) consisted of farms with infected cattle identified at slaughter in 2005 and 2006. Infections were confirmed by morphological or molecular diagnosis. The control group (n=66) comprised randomly selected farms with cattle slaughtered in the same period but with no evidence or history of infection. In personal structured interviews with the farmers, information regarding local surroundings and farm management was collected. Logistic regression revealed the following 5 factors as being positively associated with the occurrence of bovine cysticercosis: the presence of a railway line or a car park close to areas grazed by cattle, leisure activities around these areas, use of purchased roughage and organized public activities on farms attracting visitors. This information is considered useful for government authorities to direct control strategies as well as for farmers to take measures tailored to local situations.