bluuebunny/crossref_metadata_2025 huggingface dataset:
Particle swarm optimization of dipole arrays for superior MIMO capacity
Authors: Olgun Ugur , Tunc Celal Alp , Aktas Defne , Ertürk Vakur B. , Altintas Ayhan
Published: December 2008

The particle swarm optimization (PSO) technique is employed to design MIMO arrays for superior capacity. A channel model based on the method of moments solution of the electric field integral equation is utilized with PSO for arrays of dipole elements. Freestanding and printed dipole arrays are analyzed and optimized. Their adaptive performance in the MIMO channel is compared. Numerical results in the form of mean capacity, including comparisons with genetic algorithm results and measurements, are given. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 333–337, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24027
CPW‐fed ultra‐wideband antenna with dual band‐notched characteristics
Authors: Zhou Haijin , Yin Yingzeng , Deng Jingya , Liu Qizhong
Published: December 2008

In this article, the design and analysis of a CPW‐fed UWB antenna with dual band‐notched characteristics are presented. The measured bandwidth defined by VSWR <2 of the proposed antenna is from 2.8 to 11.7 GHz, except the bandwidths of 3.35–4.35 GHz for WiMAX and C‐band satellite communication, together with 5.2–5.9 GHz for WLAN. Moreover, this novel monopole antenna exhibits a nearly omnidirectional radiation pattern in the H‐plane and a dipole‐like radiation pattern in the E‐plane. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 330–332, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24030
Semi‐infinite reflection model of a multilayered dielectric through equivalent permittivity calculation
Authors: Mostarshedi S. , Richalot E. , Picon O.
Published: December 2008

This article proposes a semi‐infinite model for a multilayered dielectric. It is based on an equivalent permittivity which is valid only for reflection. Here the model is applied to building windows. Inserting the new permittivity into Green's functions associated with a semi‐infinite medium allows the fast calculation of reflected EM fields in the vicinity of building facades. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 290–294, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24032
A high‐directive bowtie radar antenna with a pyramidal reflector for ultra wideband radar imaging applications
Authors: Kwag Young K. , Hassanein Ahmed D. , Edwards David J.
Published: December 2008

We propose a novel bowtie radar antenna with a pyramidal reflector, which shows low return loss and high directional gain, capable of covering the whole ultra wideband (UWB) frequency band. The measured return loss is less than −10 dB over 3.0–11.7 GHz, and the radiation pattern is unidirectional with a high front‐to‐back ratio for UWB radar imaging applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 387–390, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24043
Elimination of the multiple‐solutions ambiguity in permittivity extraction from transmission‐only measurements of lossy materials
Authors: Hasar U. C.
Published: December 2008

A simple yet powerful method is proposed for removing the multiple solutions problem in the complex permittivity, ϵ, determination from measured transmission scattering (S‐) parameter measurements of lossy materials. The method uses amplitude‐only measurements at two slightly separated frequencies to estimate an accurate initial guess. For this purpose, we derive a one‐variable objective function for fast evaluation, which lends itself to measurement automation. The method provides an estimation for real and imaginary parts of the ϵ, which can be utilized as a measure for checking the correctness of initial ϵ estimate. The method is very useful for band‐limited measurements. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 337–341, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24048
Development of multilayer liquid crystal polymer Ka‐band downconverter modules
Authors: Aihara Kunia , Zhang Zhaonian , Pham Anh‐Vu , Zeeb David , Flack Tom , Stoneham Ed
Published: December 2008

A Ka‐band downconverter module is developed using liquid crystal polymer (LCP) thin‐film surface mount packages. The package utilizes vias to connect the RF input from the PCB signal launch onto the package substrate. The use of an LCP enclosure provides excellent moisture resistance in a compact structure. The multichip package has a measured loss of 0.4 dB at Ka‐band. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 364–367, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24051
Shielded coplanar striplines for RF integrated applications
Authors: Aziz M. Abdel , Issa H. , Kaddour D. , Podevin F. , Safwat A. M. E. , Pistono E. , Duchamp J.‐M. , Vilcot A. , Fournier J.‐M. , Ferrari P.
Published: December 2008

In this article, shielded coplanar striplines (S‐CPS) are studied to achieve slow‐wave transmission lines in a CMOS process. The slow‐wave propagation is achieved by placing floating strips below the CPS transmission line. The propagation parameters of such transmission lines are derived by simulations by means of a “full wave” 3D EM software. Quality factors as high as 35 at 10 GHz together with effective dielectric constants of 78 are reported. If these simulation results are confirmed by measurements, this would open the door to the possible realization of integrated transmission line‐based RF circuits such as power dividers, phase‐shifters, or filters of medium bandwidth below 10 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 352–358, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24054
A novel Z‐bridged electromagnetic bandgap power plane for suppression of simultaneous switching noise
Authors: Chen Wei‐Hua , Zhang Hou , Wang Jian , Shen Kai
Published: December 2008

A novel z‐bridged electromagnetic bandgap power plane is proposed for ultra‐wideband suppression of simultaneous switching noise (SSN) in high‐speed digital circuits. The z‐shaped bridge effectively increases the inductance between two adjacent unit cells. Stopband of −30 dB is realized from 260 MHz to 6.76 GHz. The excellent SSN suppression performance is validated both numerically and experimentally; good signal integrity performance can be obtained by using differential transmission lines. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 483–486, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24056
A Sierpinski‐based resonator applied for low loss and miniaturized bandpass filters
Authors: Weng Min‐Hang , Jang Ling‐Sheng , Chen Wei‐Yu
Published: December 2008

In this article, the resonant behaviors of the Sierpinski‐based fractal resonators were investigated first. The design guideline for the filter using the nth order resonator is then developed. A two‐pole filter example centered at 2.2 GHz based on the 3rd order Sierpinski‐based resonators was designed and fabricated. Measured results have a good agreement with the simulated results and verify the advantages of the size and insertion loss reduction as compared with the filter using conventional patch resonators. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 411–413, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24061
Thermal characteristics of an all‐optical add‐drop multiplexer using fiber Bragg gratings and Mach–Zehnder interferometer
Authors: Son Yong‐Hwan , Won Yong‐Yuk , Hong Moon‐Ki , Han Sang‐Kook
Published: December 2008

In this article, the output spectrum have been numerically analyzed in order to investigate the temperature characteristics of the all‐optical add/drop multiplexer. It is shown that the center Bragg wavelength shifts by about 0.014223 nm when the temperature increases by 1°C in a range of −30°C to 90°C. The experiment results show that there is a shift of about 0.011266 nm when the temperature changes by 1°C. Therefore, the center wavelength of a certain channel can be changed in case of the variation of temperature from −17°C to +17°C in the wavelength division multiplexing system with a 25‐GHz channel spacing. In addition, the performance of a certain channel can be degraded because of the crosstalk effect, which is generated among the adjacent channels, when there is a variation of temperature from +8.3°C to −8.3°C. © 2008 Wiley Periodcals, Inc. Microwave Opt Technol Lett 51: 510–513, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24065
WDM/SDM of intensity‐type fiber‐optic sensors
Authors: Jiang Yi , Tang Caijie , Zhang Fojian
Published: December 2008

A novel method for multiplexing intensity‐type fiber‐optic sensors using wavelength division multiplexing (WDM) and spatial division multiplexing (SDM) is proposed and demonstrated. A variation of ±0.2 dB at a loss of −10.95 dB is obtained, which is comparable with that obtained by the traditional method. The experimental results show that the sensor at the up‐leading fiber has no influence on the sensor at the down‐leading fiber. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 432–435, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24071
A shorted square‐ring slot antenna with a branched slot for the 1575 MHz and 2.4 GHz dual‐band operations
Authors: Tsai Chin‐Long , Deng Sheng‐Ming , Tseng Ching‐Hung , Bor Sheau‐Shong
Published: December 2008

A shorted square‐ring slot antenna with a branched slot is presented for the 1575 MHz and 2.4 GHz dual‐band operations. This proposed antenna can be designed by two steps. First, the shorted square‐ring slot antenna is designed for circular polarization in the GPS band. Then, a branched slot is added to the original structure to result linear polarization in the 2.4 GHz band. Because the added branched slot almost has no influence in the GPS band's characteristics, the design rule is very simple. The impedance and axial ratio bandwidths for the GPS band is 23.3% and 4.2%, respectively. Besides, the AR and antenna gain is 1.23 dB and 2.3 dBic at the frequency of 1575 MHz. The impedance bandwidth for the 2.4 GHz band is 4.5% and antenna gain at the center frequency of 2.445 GHz is 2.8 dBi. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 402–405, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24073
Resonance shifting and plane impedance calculations for a rectangular cavity in printed circuit board using closed form solutions
Authors: Cantrell K. , Song H.
Published: December 2008

A method for arbitrarily shifting the dominant mode frequency of a rectangular cavity in printed circuit boards (PCBs) is presented. Standard closed‐form and analytic solutions are used to determine the frequency, quality factor, and impedance of the cavity. Calculations are compared with 3D full wave finite element method (FEM) solutions. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 452–455, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24080
A 3–10 GHz CMOS low‐noise amplifier using wire bond inductors
Authors: Yang Miyoung , Ha Mincheol , Park Youngjin , Eo Yunseong
Published: December 2008

In this article, a small‐sized 3–10 GHz CMOS LNA for ultra‐wideband (UWB) applications is presented. To reduce 2 on‐chip inductors, wire bond inductors are used instead of input inductor of multisectional reactive network and source degeneration inductor. The noise figure of low‐noise amplifier (LNA) is 4 dB at minimum and IIP3 + 1.1 dBm at 5 GHz, respectively. The current consumption is 4 mA at 1.8 V supply. The LNA chip size including pads is 1 mm × 1 mm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 414–416, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24082
Uniplanar coupled‐fed printed PIFA for WWAN operation in the laptop computer
Authors: Wong Kin‐Lu , Liao Shih‐Jia
Published: December 2008

In this article, a uniplanar printed PIFA (planar inverted‐F antenna) with a coupling feed for application as an internal laptop computer antenna for penta‐band WWAN (wireless wide area network) operation is presented. The proposed PIFA has a compact structure and can be easily printed on one side of a small 0.8‐mm thick FR4 substrate of size 11 × 59 mm2, making it very promising to be embedded inside the casing of the laptop computer, especially for the thin‐profile laptop computer. With the coplanar coupling feed, the large inductive input reactance of the PIFA at around 900 MHz is compensated, and dual‐resonance excitation for the antenna's lower band at about 900 MHz is obtained, which allows it to easily cover GSM850/900 operation. A wide operating band is also achieved for the antenna's upper band at about 1900 MHz, and a bandwidth of larger than 500 MHz is obtained to cover GSM1800/1900/UMTS operation. That is, the proposed PIFA covers all the five operating bands of GSM850/900/1800/1900/UMTS for WWAN operation. Details of the proposed PIFA are presented. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 549–554, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24084
A compensated spherical reflector antenna using sub‐reflectarrays
Authors: Xu Shenheng , Rahmat‐Samii Yahya
Published: December 2008

Spherical reflectors have been used as wide‐angle scanning antennas due to the unique geometric properties of the sphere. The inherent spherical aberration, however, causes considerable performance degradation. This article presents a novel sub‐reflectarray compensating technique to correct it. A microstrip reflectarray is a planar, inexpensive, passive device with unique capabilities of controlling reflection phases. By exploiting this feasible property, it is employed as an auxiliary phase corrector, and the phase errors caused by spherical aberration are compensated. Two examples, a 35‐m spherical reflector antenna at Ka‐band and a 1.5‐m breadboard spherical reflector, are presented, and simulation results show great performance improvement for both no scan and large scan cases. Because of the difficulty in measuring large reflector antennas at UCLA, it is part of future plan to collaborate with other institutions for the verification of the concept. However, we believe that the simulation results generated in this article should provide acceptable performance prediction of the proposed antenna design. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 577–582, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24088
Erratum: Design of novel miniaturized and high quality Sierpinski square resonators
Authors: Weng Min‐Hang , Jang Ling‐Sheng , Chen Wei‐Yu , Hung Cheng‐Yuan , Yang Ru‐Yuan
Published: December 2008

Original published in Microwave Opt Technol Lett 50:1469–1471, 2008. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 583, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24089
The equiangular spiral antenna at low frequencies
Authors: McFadden Michael , Scott Waymond R.
Published: December 2008

The effect of the geometry of the equiangular spiral antenna on the lower cutoff frequency of operation is studied using the finite‐difference time‐domain method. Graphs are provided that allow calculation of the cutoff frequency from the desired performance and geometry. Additionally, the patterns of the antennas at cutoff are shown. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 536–540, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24092
A compact ultra‐wideband bandpass filter with WLAN notch band
Authors: Hsiao Pai‐Yi , Weng Ro‐Min
Published: December 2008

A compact ultra‐wideband (UWB) bandpass filter (BPF) with notch band is presented using a trilayer structure. The band elimination is essential for preventing the strong narrow band interference from the wireless local area networks within the allocated UWB spectrum. The sharp rejection of the unwanted band is introduced by adding a U‐shape resonator on the middle layer. The design is not only realized theoretically but also verified by a full‐wave electromagnetic simulation. The proposed UWB BPF is fabricated by an FR4 substrate material with the permittivity of 4.4 and the thickness of 0.8 mm. The total area is 8 mm × 6 mm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 503–507, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24093
A low power 20‐GHz low‐noise amplifier fabricated using 0.18‐μm CMOS technology
Authors: Liu J.‐X. , Kuo H.‐C. , Chu Y.‐K. , Yeh J.‐F. , Chuang H.‐R.
Published: December 2008

A 20‐GHz CMOS low‐noise amplifier (LNA) fabricated with the 0.18 μm process is presented. This two‐stage cascaded common source LNA exhibits low power consumption with a satisfying performance such as overall gain and noise figure (NF). The measurement is performed on‐wafer. The 20‐GHz LNA has demonstrated a 9.3 dB gain, a 4.4 dB NF, a −10 dBm input P1dB, and a 0.65 dBm IIP3. The power consumption is 9.6 mW from a 1.2 V power supply. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 423–426, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24098
An unconditionally stable FDTD method based on wave equation
Authors: Lin Hai , Wang Gaofeng , Liang Feng
Published: December 2008

An unconditionally stable finite‐difference time‐domain (US‐FDTD) method based on wave equation is introduced by making use of Laguerre polynomials as basis functions for expanding field components in time. This new wave‐equation‐based FDTD scheme is not only unconditionally stable but also requires less memory usage. Comparisons among the traditional FDTD, the conventional Laguerre‐polynomial US‐FDTD, and this proposed scheme are presented in the numerical examples in terms of the memory usage and computational time. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 529–532, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24101
Novel microstrip antenna element and 2‐by‐2 array for satellite TV receivers
Authors: Soliman E. A. , Affandi A. M. , Badr K. H.
Published: December 2008

A new microstrip antenna element is presented in this article. The proposed antenna is suitable for integration into an array for satellite TV receivers. It has two metal layers only, which reduces its fabrication cost significantly in comparison with other antennas with more layers. The presented results show that the proposed antenna offers wide impedance bandwidth, high isolation between feeding ports, dual‐polarization radiation, low cross‐polarization level, and high radiation efficiency. A 2‐by‐2 array based on the proposed element is also presented in this article. Planar corporate feeding networks with new routing approach are used. The presented results of the new array show that it is suitable for use as a building block for a larger array which can repalce the parabolic dish reflector in satellite TV receivers. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 458–463, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24105
60 GHz UWB over fiber system using photodiode‐based frequency up‐conversion
Authors: Gary R. , Cabon B. , Le Guennec Y.
Published: December 2008

This article describes the first optical mixing procedures for 60 GHz transmission of UWB signals, using an optical fiber for the long haul transmission and photodiode (PD)‐based up‐conversion of the UWB signal on a 60 GHz frequency carrier for picocellular network. Results show acceptable error vector magnitude (EVM) of less than 10% after optical up‐conversion. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 421–423, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24107
A tunable capacitor using a finger patterned electrode
Authors: Chul Lee Young , Hyun Ko Kyung
Published: December 2008

Using a lead zinc niobate (PZN) thin film dielectric, a tunable metal‐insulator‐metal (MIM) capacitor is presented and investigated in this article. To improve its tunability and bias characteristics, the finger patterned electrode in the top metal is devised. The capacitors were fabricated on a low‐resistivity Si substrate employing lead zinc niobate (PZN) thin film dielectric. The fabricated capacitor, whose line width and spacing was 2.5 and 2.0 μm, respectively, achieved the effective capacitance tunability of 22.9% at 5.5 V. This achieved tunability is higher value of 10% than that of the conventional rectangular MIM capacitor at 900 MHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 418–421, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24108
A theoretical structural analysis of the factors that affect 1JNH, 1hJNH and 2hJNN in N–H···N hydrogen‐bonded complexes
Authors: Alkorta Ibon , Blanco Fernando , Elguero José
Published: December 2008

Calculations of 1 JNH, 1h JNH and 2h JNN spin–spin coupling constants of 27 complexes presenting N–H·N hydrogen bonds have allowed to analyze these through hydrogen‐bond coupling as a function of the hybridization of both nitrogen atoms and the charge (+1, 0, − 1) of the complex. The main conclusions are that the hybridization of N atom of the hydrogen bond donor is much more important than that of the hydrogen bond acceptor. Positive and negative charges (cationic and anionic complexes) exert opposite effects while the effect of the transition states ‘proton‐in‐the‐middle’ is considerable. Copyright © 2008 John Wiley & Sons, Ltd.
Retrospective correction for induced magnetic field inhomogeneity in measurements of large‐vessel hemoglobin oxygen saturation by MR susceptometry
Authors: Langham Michael C. , Magland Jeremy F. , Floyd Tom F. , Wehrli Felix W.
Published: December 2008

MR susceptometry‐based blood oximetry relies on phase mapping to measure the difference in magnetic susceptibility between intravascular blood and surrounding tissue. The main source of error in MR susceptometry is the static field inhomogeneity caused by an interface between air and tissue or between adjacent tissue types. High‐pass filtering has previously been used in conjunction with shimming to reduce the effect of low spatial‐frequency modulations of the phase caused by large‐scale induced magnetic fields. We demonstrate that high‐pass filtering is not optimum for MR susceptometry because the results are sensitive to filter size. We propose an alternative method that acquires data without scanner‐implemented default shimming, and fits, after appropriate weighting and masking, the static field inhomogeneity to a second‐order polynomial. Compared to shimming the retrospective correction technique improved agreement between hemoglobin saturations measured in different segments of a vessel (femoral versus popliteal artery and vein) from three standard errors to less than one. Magn Reson Med, 2008. © 2008 Wiley‐Liss, Inc.
Binary spatial partitioning of the central‐difference time integration scheme for explicit fast transient dynamics
Authors: Casadei Folco , Halleux Jean‐Pierre
Published: December 2008

This paper proposes a generalization of the explicit central‐difference time integration scheme, using a time step variable not only in time but also in space. The solution at each element/node is advanced in time following local rather than global stability limitations. This allows substantial saving of computer time in realistic applications with non‐uniform meshes, especially in multi‐field problems like fluid–structure interactions. A binary scheme in space is used: time steps are not completely arbitrary, but stay in a constant ratio of two when passing from one partition level to the next one. This choice greatly facilitates implementation (via an integer‐based logic), ensures inherent synchronization and avoids any interpolations, necessary in other partitioning schemes in the literature, but which may reduce numerical stability. The mesh partition is automatically built up and continuously updated by simple spatial adjacency considerations. The resulting algorithm deals automatically with large variations in time of stability limits. The paper introduces the core spatial partitioning technique in the Lagrangian formulation. Some academic numerical examples allow a detailed comparison with the standard, spatially uniform algorithm. A final more realistic example shows the application of partitioning in simulations with arbitrary Lagrangian Eulerian formulation and fully‐coupled boundary conditions (fluid–structure interaction). Copyright © 2008 John Wiley & Sons, Ltd.
Frameshift mutations of autophagy‐related genes ATG2B, ATG5, ATG9B and ATG12 in gastric and colorectal cancers with microsatellite instability
Authors: Kang Mi Ran , Kim Min Sung , Oh Ji Eun , Kim Yoo Ri , Song Sang Yong , Kim Sung Soo , Ahn Chang Hyeok , Yoo Nam Jin , Lee Sug Hyung
Published: December 2008

Mounting evidence indicates that alterations of autophagy processes are directly involved in the development of many human diseases, including cancers. Autophagy‐related gene (ATG) products are main players in the autophagy process. In humans there are 16 known ATG genes, of which four (ATG2B, ATG5, ATG9B and ATG12) have mononucleotide repeats with seven or more nucleotides. Frameshift mutations of genes with mononucleotide repeats are features of cancers with microsatellite instability (MSI). It is not known whether ATG genes with mononucleotide repeats are altered by frameshift mutations in gastric and colorectal carcinomas with MSI. For this, we analysed the mononecleotide repeats in ATG2B, ATG5, ATG9B and ATG12 in 32 gastric carcinomas with high MSI (MSI‐H), 13 gastric carcinomas with low MSI (MSI‐L), 43 colorectal carcinomas with MSI‐H and 15 colorectal carcinomas with MSI‐L by a single‐strand conformation polymorphism (SSCP) analysis. We found ATG2B, ATG5, ATG9B and ATG12 mutations in 10, 2, 13 and 0 cancers, respectively. The mutations were detected in MSI‐H cancers but not in MSI‐L cancers. Gastric and colorectal cancers with MSI‐H harboured one or more ATG mutations in 28.1% and 27.9%, respectively. Our data indicate that frameshift mutations in ATG genes with mononucleotide repeats are common in gastric and colorectal carcinomas with MSI‐H, and suggest that these mutations may contribute to cancer development by deregulating the autophagy process. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
A combined experimental and theoretical investigation on the oxygenation of organic sulfides by oxo(salen)chromium(V) ion
Authors: Venkataramanan Natarajan Sathiyamoothy , Rajagopal Seenivasan , Suvitha Ambigapathy , Kawazoe Yoshiyuki
Published: December 2008

The mechanism of oxygenation of organic sulfide by oxo(salen)chromium(V) complexes has been studied experimentally and by the density functional theory (DFT) method. Spectral studies show DMSO ligands bind with the Cr center of oxidant and the adduct formed was responsible for the oxygenation reaction. The reaction was first order with respect to oxidant and substrate. Hammett plot shows the formation of positive charge over sulfur atom and the development of negative charge over the oxidant in the transition state (TS). For the substrate ρ values are in the range from −1.5 to −1.8. The geometry has been correctly predicted by the B3LYP function, and it gives better results for spin states, harmonic frequencies, and thermodynamic energies for the system. DFT results indicate the existence of oxo(salen)chromium(V) and Cr(III)–salen at doublet and quartet as ground state, respectively. Binding of donor ligand weakens the CrO bond. TS structures show an increase in the negative charge and spin density over Cr atom indicating the involvement of spin inversion and radical character. The low activation energy and high free energy change are responsible for the enhancement of the reaction rate and product yield in the presence of DMSO donor ligand, while the rebound mechanism and the direction of substrate approach perpendicular to the salen plane are responsible for their higher selectivity. From this combined study, a mechanism involving consecutive two‐electron transfer from the oxo(salen)chromium(V) ion to the electron‐rich sulfur atom is proposed. Copyright © 2008 John Wiley & Sons, Ltd.
Copolymerization of tetradecene‐1 and octene‐1 with silyl‐protected 10‐undecen‐1‐ol using a Cs‐symmetry hafnium metallocene catalyst. A route to functionalized poly(α‐olefins)
Authors: Kotzabasakis Vasilios , Petzetakis Nikolaos , Pitsikalis Marinos , Hadjichristidis Nikos , Lohse David J.
Published: December 2008

Statistical copolymers of tetradecene‐1 and octene‐1 with 1‐tert‐butyldimethylsilyloxy‐10‐undecene were synthesized by metallocene catalyzed copolymerization. The Cs‐symmetry hafnium metallocene [(p‐Et3Si)Ph]2C(2,7‐di‐tert‐BuFlu)(Cp)Hf(CH3)2 and tetrakis(pentafluorophenyl) borate dimethylanilinium salt ([B(C6F5)4]−[Me2NHPh]+) were employed as the catalytic system, in the presence of trioctylaluminum (TOA) as a scavenger. The monomer reactivity ratios were calculated using the Finemann‐Ross, inverted Finemann‐Ross, and Kelen‐Tüdos graphical methods. The structural parameters of the different copolymers were obtained from the calculation of the dyad monomer sequence fractions and the mean sequence lengths derived via the reactivity ratios. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 876–886, 2009
Kinetic pathway investigations of three‐component photoinitiator systems for visible‐light activated free radical polymerizations
Authors: Kim Dongkwan , Stansbury Jeffrey W.
Published: December 2008

Three‐component photoinitiator systems generally include a light‐absorbing photosensitizer (PS), an electron donor, and an electron acceptor. To investigate the key factors involved with visible‐light activated free radical polymerizations involving three‐component photoinitiators and 2‐hydroxyethyl methacrylate, we used thermodynamic feasibility and kinetic considerations to study photopolymerizations initiated with either rose bengal or fluorescein as the PS. The Rehm–Weller equation was used to verify the thermodynamic feasibility for the photo‐induced electron transfer reaction. It was concluded that key kinetic factors for efficient visible‐light activated initiation process are summarized in two ways: (1) to retard back electron transfer and recombination reaction steps and (2) to use a secondary reaction step for consuming dye‐based radical and regenerating the original PS (dye). Using the thermodynamic feasibility and kinetic data, we suggest three different kinetic mechanisms, which are (i) photo‐reducible series mechanism, (ii) photo‐oxidizable series mechanism, and (iii) parallel‐series mechanism. Because the photo‐oxidizable series mechanisms most efficiently allow the key kinetic factors, this kinetic pathway showed the highest conversion and rate of polymerization. The kinetic data measured by near‐IR and photo‐differential scanning calorimeter verified that the photo‐oxidizable series mechanism provides the most efficient kinetic pathway in the visible‐light activated free radical polymerizations. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 887–898, 2009
Ring‐opening polymerization of benzylated 1,6‐anhydro‐β‐D‐lactose and specific biological activities of sulfated (1→6)‐α‐D‐lactopyranans
Authors: Han Shuqin , Kanematsu Yuji , Hattori Kazuyuki , Nakashima Hideki , Yoshida Takashi
Published: December 2008

A new anhydro disaccharide monomer, 1,6‐anhydro‐2,3‐di‐o‐benzyl‐4‐o‐(2′,3′,4′,6′‐tetra‐o‐benzyl‐β‐D‐galactopyranosyl)‐β‐D‐glucopyranose (benzylated 1,6‐anhydro lactose (LSHBE)), was synthesized from D‐lactose to investigate the polymerizability and biological activities of the resulting branched polysaccharides. The ring‐opening polymerization of LSHBE was carried out with phosphorus pentafluoride as a catalyst under high vacuum to give a stereoregular benzylated (1 → 6)‐α‐D‐lactopyranan. The molecular weights of poly(LSHBE)s increased with an increase in the amount of CH2Cl2 solvent, and polymerization temperatures were affected in both molecular weights and yields of the polymers. The copolymerization of LSHBE with benzylated 1,6‐anhydro‐β‐D‐glucopyranose (LGTBE) gave the corresponding copolysacchrides having different proportions of lactose and glucose units in good yields. After debenzylation to recover hydroxyl groups and then sulfation, sulfated homopoly(lactose)s and copoly(lactose and glucose)s were obtained. Sulfated homopoly(lactose)s had moderate anti‐HIV (EC50 = 5.9 and 1.3 μg/mL) and blood anticoagulant activities (AA = 18 and 13 unit/mg), respectively. Sulfated copoly(lactose and glucose) having 15 mol % lactose units gave high anti‐HIV and blood anticoagulant activities of 0.3 μg/mL and 54 unit/mg, respectively. These biological results suggest that the distance between branched units on the main chain plays an important role in the anti‐HIV and blood anticoagulant activities. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 913–924, 2009
Equations of state for polyamide‐6 and its nanocomposites. 1. Fundamentals and the matrix
Authors: Utracki L. A.
Published: December 2008

The pressure‐volume‐temperature (PVT) surface of polyamide‐6 (PA‐6) was determined in the range of temperature T = 300–600 K and pressure P = 0.1–190 MPa. The data were analyzed separately for the molten and the noncrystalline phase using the Simha‐Somcynsky (S‐S) equation of state (eos) based on the cell‐hole theory. At Tg(P) ≤ T ≤ Tm(P), the “solid” state comprises liquid phase with crystals dispersed in it. The PVT behavior of the latter phase was described using Midha‐Nanda‐Simha‐Jain (MNSJ) eos based on the cell theory. The data fitting to these two theories yielded two sets of the Lennard‐Jones interaction parameters: ε*(S‐S) = 34.0 ± 0.3 and ε*(MNSJ) = 22.8 ± 0.3 kJ/mol, whereas v*(S‐S) = 32.00 ± 0.1 and v*(MNSJ) = 27.9 ± 0.2 mL/mol. The raw PVT data were numerically differentiated to obtain the thermal expansion and compressibility coefficients, α and κ, respectively. At constant P, κ followed the same dependence on both sides of the melting zone near Tm. By contrast, α = α(T) dependencies were dramatically different for the solid and molten phase; at T < Tm, α linearly increased with increasing T, then within the melting zone, its value step‐wise decreased, to slowly increase at higher temperatures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 299–313, 2009
Beyond the psychotherapy and survival debate: the challenge of social disparity, depression and treatment adherence in psychosocial cancer care
Authors: Kissane David
Published: December 2008

The psychotherapy and cancer survival debate generated great interest in the psychoneuroimmunological and bio‐behavioral mechanisms that might mediate any gain in survival. Recent methodologically‐improved cognitive‐existential, supportive‐expressive and psycho‐educational group interventions for patients with breast cancer and melanoma have not extended survival times. Shorter survival has been associated with social disparity and untreated clinical depression, potentially mediated by poorer adherence to anti‐cancer treatments. Group therapy both prevents and treats depression. Future research could address these bio‐behavioral mechanisms. Copyright © 2008 John Wiley & Sons, Ltd.
Nanocomposites of Electrospun Poly[(D,L‐lactic)‐co‐(glycolic acid)] and Plasma‐Functionalized Single‐Walled Carbon Nanotubes for Biomedical Applications
Authors: Yoon Ok J. , Kim Hyun W. , Kim Duck J. , Lee Hyun J. , Yun Ji Y. , Noh Yoo H. , Lee Do Y. , Kim Do H. , Kim Sung S. , Lee Nae‐Eung
Published: December 2008

The conductance of amine‐functionalized SWCNTs (a‐SWCNTs), obtained by inductively coupled N2/H2 plasma treatment of commercially available carboxyl‐functionalized SWCNTs (c‐SWCNTs), was decreased compared to that of the c‐SWCNTs. As a result, the diameter and surface energy of electrospun PLGA/a‐SWCNT nanocomposites decreased and increased, respectively, compared to those of electrospun PLGA/c‐SWCNT nanocomposites. The results also showed that the a‐SWCNTs were well dispersed in the nanocomposites, improved adhesion of SWCNTs to the surrounding polymer matrix and thereby enhanced the tensile modulus of electrospun PLGA/c‐SWCNT and PLGA/a‐SWCNT nanocomposites by 127 and 226%, respectively, compared to that of electrospun PLGA membranes.

magnified image
The vitamin D receptor agonist elocalcitol inhibits IL‐8‐dependent benign prostatic hyperplasia stromal cell proliferation and inflammatory response by targeting the RhoA/Rho kinase and NF‐kB pathways
Authors: Penna Giuseppe , Fibbi Benedetta , Amuchastegui Susana , Corsiero Elisa , Laverny Gilles , Silvestrini Enrico , Chavalmane Aravinda , Morelli Annamaria , Sarchielli Erica , Vannelli Gabriella Barbara , Gacci Mauro , Colli Enrico , Maggi Mario , Adorini Luciano
Published: December 2008

BACKGROUND

Benign prostatic hyperplasia (BPH) is characterized by an important inflammatory component. Stimulation of human prostate stromal cells from BPH tissues with proinflammatory cytokines leads to secretion of IL‐8, a chemokine involved in BPH pathogenesis. The vitamin D receptor (VDR) agonist elocalcitol can arrest prostate growth in BPH patients, but its mechanism of action in this pathology is still incompletely understood.

METHODS

IL‐8 levels were measured by real‐time RT‐PCR and ELISA. NF‐κB translocation and COX‐2 expression were evaluated by confocal microscopy. RhoA and Rho‐kinase (ROCK) gene expression and functional activity were studied by real‐time RT‐PCR, immuno‐kinase assays, Western blot analysis, confocal microscopy, and cell invasion.

RESULTS

Stimulation of BPH cells with IL‐8 activates the calcium‐sensitizing RhoA/ROCK pathway, as demonstrated by the increased membrane translocation of RhoA and by phosphorylation of the ROCK substrate myosin phosphatase target subunit 1 (MYPT‐1). In agreement with these data, C3 exoenzyme, a selective RhoA inhibitor, inhibits IL‐8‐induced invasion of BPH cells. The VDR agonist elocalcitol significantly inhibits IL‐8 production by BPH cells stimulated with inflammatory cytokines, and IL‐8‐induced proliferation of BPH cells. In addition, elocalcitol inhibits IL‐8‐induced membrane translocation of RhoA and MYPT‐1 phosphorylation in BPH cells, and inhibits dose‐dependently their IL‐8‐dependent invasion. The inhibition induced by elocalcitol of IL‐8 production by BPH cells is accompanied by decreased COX‐2 expression and PGE2 production and by arrest of NF‐κB p65 nuclear translocation, associated with inhibition of the RhoA/ROCK pathway.

CONCLUSIONS

These data provide a mechanistic explanation for the anti‐proliferative and anti‐inflammatory properties of elocalcitol in BPH cells. Prostate 69:480–493, 2009. © 2008 Wiley‐Liss, Inc.
Butanol fraction containing berberine or related compound from nexrutine® inhibits NFκB signaling and induces apoptosis in prostate cancer cells
Authors: Muralimanoharan Sri Balasubashini , Kunnumakkara A.B. , Shylesh Bhaskaran , Kulkarni Kaustubh H. , Haiyan Xu , Ming Hu , Aggarwal Bharat B. , Rita Ghosh , Kumar Addanki P.
Published: December 2008

BACKGROUND

Epidemiological and laboratory studies support the hypothesis that several plant components influence prostate carcinogenesis and holds promise for disease prevention. Previously we reported that Nexrutine® (bark extract from Phellodendron amurense) inhibits proliferation of prostate cancer cells and prostate tumor development in the transgenic adenocarcinoma of mouse prostate (TRAMP) model through modulation of Akt signaling pathway. In the present investigation we conducted studies to further define the mechanism of action of Nexrutine® and to identify the active component associated with its biological activity.

METHODS

Androgen‐responsive, androgen‐independent human prostate cancer cell lines and tissues from TRAMP mice fed Nexrutine® were used in these studies. Activity guided fractionation identified butanol fraction recapitulating the activities of Nexrutine® assessed by proliferation assays, apoptotic assays (DAPI and TUNEL staining), transient transfections, gel shift assays and Western blotting. In addition ultra‐performance liquid chromatography (UPLC) of butanol fraction was used to identify active component of Nexrutine®.

RESULTS

Butanol fraction recapitulated the activities of Nexrutine® in (i) inhibiting proliferation; (ii) inducing apoptosis; and (iii) modulating transcriptional activity of NFκB in prostate cancer cells. Our data also indicates that both Nexrutine® and butanol fraction modulates NFκB transcriptional activity by inhibiting IκBα phosphorylation. Expression of p65 and phosphorylated IκBα are high in tumors from TRAMP mice. In contrast dietary administration of Nexrutine® reduced expression of p65 and phosphorylated IκBα in prostate from TRAMP mice. In addition using UPLC, we have identified berberine or closely related compound in the butanol fraction.

CONCLUSION

The results suggest that berberine or closely related component of butanol fraction may be responsible for the observed biological activities and induce apoptosis in prostate cancer cells by targeting critical cell survival signaling pathways both in vitro and in vivo. Prostate 69:494–504, 2009. © 2008 Wiley‐Liss, Inc.
Conserved structural and dynamics features in the denatured states of drosophila SUMO, human SUMO and ubiquitin proteins: Implications to sequence‐folding paradigm
Authors: Kumar Dinesh , Chugh Jeetender , Sharma Shilpy , Hosur Ramakrishna V.
Published: December 2008

We have characterized here the structural and dynamics properties of urea‐denatured state of dSmt3 by multidimensional NMR at 27°C and pH 5.6. The various results suggest that hydrophobic clusters as well as different native and non‐native secondary structural elements are transiently formed. The backbone in the regions Gln26‐Lys31 and Gly47‐Gln60 shows conformationally restricted motions. The AABUF profile of the sequence reflected that this region has the highest tendency to undergo hydrophobic clustering and may thus assist the formation of transient structures. The secondary chemical shifts and coupling constants indicated that this region has strong tendency to occupy the broad β‐domain of (ϕ,ψ) space. A number of NMR parameters indicated that the region Asp58‐Gln60 (corresponding to β3‐β4 turn in the folded state) has residual turn‐like structure. The present structural and dynamics results on urea‐denatured dSmt3 have been compared with the previously published results on denatured states of similar fold proteinse.g. human SUMO‐1 (55% homologous), ubiquitin (13.8% homologous) and GB1. Although the sequence homology is rather poor between them, the residual structure in all cases seems to be largely native type. The implications of these to sequence‐folding paradigm and initial folding processes have been discussed. Proteins 2009. © 2008 Wiley‐Liss, Inc.
Characterization of a diagnostic Fab fragment binding trimeric Lewis X
Authors: de Geus Daniël C. , van Roon Anne‐Marie M. , Thomassen Ellen A. J. , Hokke Cornelis H. , Deelder André M. , Abrahams Jan Pieter
Published: December 2008

Lewis X trisaccharides normally function as essential cell–cell interaction mediators. However, oligomers of Lewis X trisaccharides expressed by the parasite Schistosoma mansoni seem to be related to its evasion of the immune response of its human host. Here we show that monoclonal antibody 54‐5C10‐A, which is used to diagnose schistosomiasis in humans, interacts with oligomers of at least three Lewis X trisaccharides, but not with monomeric Lewis X. We describe the sequence and the 2.5 Å crystal structure of its Fab fragment and infer a possible mode of binding of the polymeric Lewis X from docking studies. Our studies indicate a radically different mode of binding compared to Fab 291‐2G3‐A, which is specific for monomeric Lewis X, thus providing a structural explanation of the diagnostic success of 54‐5C10‐A. Proteins 2009. © 2008 Wiley‐Liss, Inc.
Description and recognition of regular and distorted secondary structures in proteins using the automated protein structure analysis method
Authors: Ranganathan Sushilee , Izotov Dmitry , Kraka Elfi , Cremer Dieter
Published: December 2008

The Automated Protein Structure Analysis (APSA) method, which describes the protein backbone as a smooth line in three‐dimensional space and characterizes it by curvature κ and torsion τ as a function of arc length s, was applied on 77 proteins to determine all secondary structural units via specific κ(s) and τ(s) patterns. A total of 533 α‐helices and 644 β‐strands were recognized by APSA, whereas DSSP gives 536 and 651 units, respectively. Kinks and distortions were quantified and the boundaries (entry and exit) of secondary structures were classified. Similarity between proteins can be easily quantified using APSA, as was demonstrated for the roll architecture of proteins ubiquitin and spinach ferridoxin. A twenty‐by‐twenty comparison of all α domains showed that the curvature‐torsion patterns generated by APSA provide an accurate and meaningful similarity measurement for secondary, super secondary, and tertiary protein structure. APSA is shown to accurately reflect the conformation of the backbone effectively reducing three‐dimensional structure information to two‐dimensional representations that are easy to interpret and understand. Proteins 2009. © 2008 Wiley‐Liss, Inc.
Estimating flame speeds for use with the BST blast curves
Authors: Melton Timothy A. , Marx Jeffrey D.
Published: December 2008

The Baker‐Strehlow‐Tang (BST) vapor cloud explosion model is one of the most common methods used to estimate overpressures for the purpose of locating buildings in relation to process units. This model suffers from a problem common to all simplified explosion models: the user is required to pick the “strength” of the explosion using one or more simple parameters. In the BST model, the fuel reactivity, flame expansion, and obstacle density parameters are used to select a flame speed from a limited matrix of possible values. This article presents the Quest Model for estimation of flame speeds (QMEFS), a systematic approach to estimating flame speed that does not rely on the BST categories. It provides for a continuous range of flame speeds that can then be used with the existing BST blast curves to calculate the characteristics of the vapor cloud explosion. The QMEFS approach provides the user with a method for describing a vapor cloud explosion that is more detailed than the BST model, and establishes a more refined system for predicting the consequences of vapor cloud explosions. © 2008 American Institute of Chemical Engineers Process Saf Prog, 2009
The persisting challenge of selective and specific proteasome inhibition
Authors: Groll Michael , Huber Robert , Moroder Luis
Published: December 2008

Since the discovery of the proteasome and its structure elucidation intensive research programs in academic institutions and pharmaceutical industries led to identification of a wide spectrum of synthetic and natural small proteasomal inhibitors. Activity studies with these small molecules helped to deeply understand the complex biochemical organization and functioning of the proteasome. The new structural and biochemical insights placed the proteasome as an important anti‐cancer drug target, as revealed by the dipeptide boronate proteasome inhibitor, bortezomib, which is currently used for treatment of multiple myeloma. Serious side effects and partial cell resistance against bortezomib demand creation and discovery of new improved generations of more specific and potent proteasomal inhibitors. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.