bluuebunny/crossref_metadata_2025 huggingface dataset:
The major subtypes of human B‐cell lymphomas lack mutations in BCL‐2 family member BAD
Authors: Schmitz Roland , Thomas Roman K. , Harttrampf Anne C. , Wickenhauser Claudia , Schultze Joachim L. , Hansmann Martin‐Leo , Wolf Jürgen , Küppers Ralf
Published: April 2006

Members of the BCL‐2 gene family are well known for their role in the pathogenesis of B‐cell lymphomas in humans and in mouse models. A recent report that knockout mice deficient for the proapoptotic BCL‐2 family member gene BAD frequently develop B‐cell lymphomas prompted us to analyze a large collection of human B‐cell lymphomas for inactivating mutations in the BAD gene. All 3 exons of the BAD gene were amplified and directly sequenced. The 81 lymphomas analyzed included 16 cases of B‐cell chronic lymphocytic leukemia, 11 mantle‐cell lymphomas, 10 follicular lymphomas, 7 MALT lymphomas, 8 Burkitt's lymphoma cell lines, 3 cell lines of multiple myeloma, 15 cases and 4 cell lines of diffuse large B‐cell lymphoma and 7 Hodgkin's lymphoma lines. No mutations were found in any of the cases. We conclude that mutations in the BAD gene do not play a role in the pathogenesis of the major subtypes of human B‐cell lymphomas. © 2006 Wiley‐Liss, Inc.
Down‐regulation of ASY/Nogo transcription associated with progression of adult T‐cell leukemia/lymphoma
Authors: Shimakage Misuzu , Inoue Nobumasa , Ohshima Kohichi , Kawahara Kunimitsu , Oka Takashi , Yasui Kazuta , Matsumoto Kayoko , Inoue Hirokazu , Watari Akihiro , Higashiyama Shinji , Yutsudo Masuo
Published: April 2006

Adult T‐cell leukemia/lymphoma (ATLL) is an aggressive form of human leukemia/lymphoma. Although this disease is initiated by infection with human T‐lymphotropic virus type 1 (HTLV‐1), many HTLV‐1 carriers survive for a long period without aggressive illness, suggesting that other factors may play roles in the progression of ATLL to an aggressive state. However, the mechanism involved in this progression still remains unclear. Previously, we have reported that ASY/Nogo mRNA was markedly down‐regulated in human small‐cell lung carcinomas, whereas it was expressed in normal tissues and other lung carcinomas, such as adenocarcinoma and squamous cell carcinoma. To understand whether or not ASY/Nogo gene is involved in the progression of ATLL, we examined the expression of ASY/Nogo mRNA in smoldering, chronic and aggressive ATLL, and found that the expression level of ASY/Nogo mRNA was markedly reduced in clinically aggressive ATLL. HTLV‐1 Tax expression was not affected by the down‐regulation of ASY/Nogo mRNA. These results indicate that the ASY/Nogo gene may act as a suppressor against ATLL progression, independent of Tax expression. © 2006 Wiley‐Liss, Inc.
Cd8 T‐cell recognition of human 5T4 oncofetal antigen
Authors: Smyth Lucy JC , Elkord Eyad , Taher Taher E.I. , Jiang Hui‐Rong , Burt Deborah J. , Clayton Alison , van Veelen Peter A. , de Ru Arnoud , Ossendorp Ferry , Melief Cornelis J. M. , Drijfhout Jan W. , Dermime Said , Hawkins Robert E. , Stern Peter L.
Published: April 2006

The 5T4 oncofetal antigen is expressed by a wide variety of human carcinomas, including colorectal, ovarian and gastric carcinomas. The restricted expression of 5T4 on tumor tissues as well as its implication in tumor progression and bad prognosis makes 5T4 a promising new candidate for immunotherapy. An MVA vaccine encoding 5T4 antigen has been successfully evaluated in preclinical studies in a murine tumor model. Here, we report the generation of human CD8 T cells specific for the 5T4 antigen by stimulation with autologous monocyte derived DC infected with a replication defective adenovirus encoding the 5T4 cDNA (Ad5T4). Analysis of several donors confirms a repertoire of such CD8 responses. In a parallel approach, incorporating the results of proteasome‐mediated digestion of 5T4 derived 35‐mer peptides and the potential high affinity epitopes predicted by a computer‐based algorithm, we identified 8 putative HLA‐A*0201‐presented CD8 MHC class I epitopes of 5T4 antigen. Two of these generated specific CD8 T cells after restimulation with peptide loaded autologous DC and assay by cytotoxicity and IFNγ ELISPOT. Moreover these particular peptide generated T cells recognized naturally 5T4 positive tumor cells only if they expressed HLA‐A*0201 as judged by IFNγ ELISPOT or ELISA. Also, HLA‐A*0201 CD8 T cells recognized these peptides in a DC‐Ad5T4 polyclonal response. In conclusion, there is a repertoire of CD8 T cell recognition of 5T4 in normal human donors and some candidate HLA‐A*0201 epitopes have been identified. © 2006 Wiley‐Liss, Inc.
Nuclear Ptdlns(3,4,5)P3 signaling: An ongoing story
Authors: Déléris Paul , Gayral Stéphanie , Breton‐Douillon Monique
Published: April 2006

Phosphatidylinositol 3,4,5‐trisphosphate (Ptdlns(3,4,5)P3) is linked to a variety of cellular functions, such as growth, cell survival, and differentiation. Ptdlns(3,4,5)P3 is primarily synthesized by class I phosphoinositide 3‐kinases and its hydrolysis by two 3‐phosphoinositide 3‐phosphatases, PTEN and SHIP proteins, leads to the production of two other second messengers, Ptdlns(4,5)P2 and Ptdlns(3,4)P2, respectively. Evidence accumulated over the last years strongly suggest that Ptdlns(3,4,5)P3 is an important component of signaling pathway operating within the nucleus. Moreover, recent advances indicated that nuclear translocation of cell surface receptors could activate nuclear phosphoinositide 3‐kinase suggesting a new mode of signal transduction. The aim of this review is intended to summarize the state of our knowledge on nuclear Ptdlns(3,4,5)P3 and its metabolizing enzymes, and to highlight the emerging roles for intranuclear Ptdlns(3,4,5)P3. J. Cell. Biochem. 98: 469–485, 2006. © 2006 Wiley‐Liss, Inc.
Friedel–Crafts benzylation of aromatics with benzyl alcohols catalyzed by heteropoly acids supported on mesoporous silica
Authors: Kamalakar Gunda , Komura Kenichi , Kubota Yoshihiro , Sugi Yoshihiro
Published: April 2006

Heteropoly acids (HPA), such as tungstophosphoric acid (H3PW12O40 · xH2O) (HPW), molybdophosphoric acid (H3PMo12O40 · xH2O) (HPMo) and tungstosilicic acid (H4SiW12O40 · xH2O) (HSiW) were supported on mesoporous silica such as MCM‐41, FSM‐16 and SBA‐15 by the impregnation method to enhance the catalytic activity of these solid acids by their dispersion on the support with high surface area. These supported solid catalysts were used in the benzylation of benzene and substituted aromatics with benzyl alcohol (BnOH). The immobilization enhanced the catalytic performances and HPW supported on MCM‐41 exhibited the best activity for benzylation among the heteropoly acids, although dibenzyl ether (DBE) formation by the dehydration of BnOH also occurred. The mesoporous architecture of the silica enhances the activity of benzylation because of the high dispersion of HPW on the support with high surface area; however, no steric restriction by the pores of mesoporous silica was observed. The catalysts used in the present study retained their catalytic activity for five reaction cycles. The rate of benzylation of substituted benzenes and benzylating agents was influenced by the electronic nature of the substituent. Electron‐donating groups enhanced the rate of reaction; however, electron‐withdrawing groups retard the benzylation. These results show that the reactivity of benzene and benzyl alcohols was retarded by electron‐withdrawing groups. The formation of polybenzylated products was influenced by the reactivity of diphenylmethane products. The benzylation accompanies the DBE formation by the dehydration of BnOH, particularly in the initial stages, because the benzylation of aromatics with BnOH is not as rapid as the dehydration of BnOH. However, direct benzylation of benzene occurs with DBE and DBE participates in the benzylation of benzene via BnOH after its hydrolysis. This is further supported by the effect of water on the benzylation of benzene by DBE, although there is a possibility of direct benzylation of DBE with benzene. Copyright © 2006 Society of Chemical Industry
Nanometric crystal defects in transmission electron microscopy
Authors: Schäublin Robin
Published: April 2006

Transmission electron microscopy (TEM) is revisited in order to define methods for the identification of nanometric defects. Nanometric crystal defects play an important role as they influence, generally in a detrimental way, physical properties. For instance, radiation‐induced damage in metals strongly degrades mechanical properties, rendering the material stronger but brittle. The difficulty in using TEM to identify the nature and size of such defects resides in their small size. TEM image simulations are deployed to explore limits and possible ways to improve on spatial resolution and contrast. The contrast of dislocation loops, cavities, and a stacking fault tetrahedra (SFT) are simulated in weak beam, interfering reflections (HRTEM), and scanned condensed electron probe (STEM) mode. Results indicate that STEM is a possible way to image small defects. In addition, a new objective aperture is proposed to improve resolution in diffraction contrast. It is investigated by simulations of the weak beam imaging of SFT and successfully applied in experimental observations. Microsc. Res. Tech. 69:305–316, 2006. © 2006 Wiley‐Liss, Inc.
Atomic scale defect analysis in the scanning transmission electron microscope
Authors: Arslan Ilke , Browning Nigel D.
Published: April 2006

Z‐contrast imaging and electron energy loss spectroscopy in the scanning transmission electron microscope provide the ability to investigate the structure–composition–property relationship at individual defects on the atomic scale. In this article, the main principles behind the techniques will be described. The application of these methods to the analysis of individual dislocations in GaN will also be discussed. In this case, the atomic scale methods indicate that many of the structural and electronic properties of dislocations are modified by the presence of impurities, such as oxygen. Microsc. Res. Tech 69:330–342, 2006. Published 2006 Wiley‐Liss, Inc.
Design and analysis of fMRI studies with neurologically impaired patients
Authors: Price Cathy J. , Crinion Jenny , Friston Karl J.
Published: April 2006

Functional neuroimaging can be used to characterize two types of abnormality in patients with neurological deficits: abnormal functional segregation and abnormal functional integration. In this paper we consider the factors that influence the experimental design, analysis, and interpretation of such studies. With respect to experimental design, we emphasize that: 1) task selection is constrained to tasks the patient is able to perform correctly, and 2) the most sensitive designs entail presenting stimuli of the same type close together. In terms of data preprocessing, prior to statistical analysis, we note that structural pathology may call for constraints on nonlinear transformations, used by spatial normalization, to prevent distortion of intact tissue. This means that one may have to increase spatial smoothing to reduce the impact of inaccurate normalization. Important issues in statistical modeling concern the first level of analysis (estimation of activation within subject), which has to distinguish correct from incorrect responses. At the second level (between subjects), inference should be based on between‐subjects variance. Provided that these and other constraints are met, deficits in functional segregation are indicated when activation in one or a set of regions is higher or lower in patients relative to control subjects. In contrast, deficits in functional integration are implied when the influence of one brain region on another is stronger or weaker in patients relative to control subjects. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Cover Picture: Macromol. Chem. Phys. 9/2006
Authors: Huang Jinyu , Jia Shijun , Siegwart Daniel J. , Kowalewski Tomasz , Matyjaszewski Krzysztof
Published: April 2006

Cover: Well‐defined PS(core)‐PnBA tri‐arm star block copolymers synthesized via ATRP tend to aggregate with distinct bulky PS cores and PnBA chains emanating outward as visualized by AFM. Aggregates with n = 2 and 3 dominate and most aggregates have “n×3” arms but minor amounts of “defective” stars with missing arms are also observed. The AFM analysis shows that PS core star block copolymers contain˜92% tri‐arm star block copolymers, and efficiency of cross‐propagation is 97.3%. Further details can be found in the Full Paper by J. Huang, S. Jia, D. J. Siegwart, T. Kowalewski, and K. Matyjaszewski* on page 801.
What is Conservation Science?
Authors: Townsend Joyce H.
Published: April 2006

‘Conservation science’ or ‘cultural heritage research’ is defined through a discussion of research needs, training and employment patterns world‐wide, and trends in published work. Parallels with mainstream polymer science are drawn throughout. Some aspects are discussed in more detail: traditional paint composites; studies in modern, synthetic, paint composites; the relevance of accelerated ageing to a range of polymer types.
State of Art in the SIMS (Secondary Ion Mass Spectrometry) Application to Archaeometry Studies
Authors: Anderle Mariano , Bersani Massimo , Vanzetti Lia , Pederzoli Simone
Published: April 2006

One of the main problems of cultural heritages in all the different forms (buildings, monuments, painting) is their deterioration caused by natural and artificial decay processes. To address the conservation issue specific studies are required to determine, for example, origin, date, materials composition, technology processes involved, etc. The use of microanalysis techniques, in particular secondary ion mass spectrometry (SIMS), in the cultural heritage area has been demonstrated extremely useful to approach and provide this kind of information and support the experts involved in studies within this area (art historians, archaeologists, curators etc.). In this work, an up to date overview of possible SIMS applications to archaeological topics is given, pointing out the peculiarity and the main limitations and drawbacks of this analytical approach. One example of SIMS application to archaeological glasses is reported. Moreover the wide technique flexibility and its strength in combination with other complementary techniques are remarked.
Degradation of PEG in the Warship Vasa
Authors: Glastrup Jens , Shashoua Yvonne , Egsgaard Helge , Mortensen Martin Nordvig
Published: April 2006

The distribution and ageing of polyethylene glycol (PEG) in the Vasa warship has been examined and compared with other archaeological shipwrecks which have also been impregnated with PEG. The distribution of the PEG has been characterised using a variety of mass spectrometric and FT‐IR techniques. Our results show that the PEG after 30 years is still in a reasonably good condition, with a molecular weight distribution that resembles fresh PEG. Only minor levels of degradation products were found. It seems that the PEG preserved wood contains an increased amount of formic acid and the results suggest that it originates from the PEG. Acetic acid is also present; this probably originates from the wood.
Nanotechnology for Vasa Wood De‐Acidification
Authors: Chelazzi David , Giorgi Rodorico , Baglioni Piero
Published: April 2006

The conservation of the seventeenth‐century Swedish warship Vasa is a challenge due the unique history of its recovery and the delicate interventions made for its preservation. In the past years the strong acidity of wood came out as a threat for its conservation. The large amount of sulfur, produced by metabolic action of bacteria in the seabed, partly converted to sulfuric acid, catalyzes the chemical degradation of the wood through the acid hydrolysis of cellulose. This contribution reviews recent studies on the degradation of Vasa wood. We show how wood acidity can be neutralized by the application of calcium or magnesium hydroxide nanoparticles, forming an alkaline reservoir inside the wood that protect it from further acid attack. This has been evidenced by the thermal analysis carried out on fresh wood, Vasa wood, artificially degraded wood, and paper samples studied as reference cellulose‐made materials. Pyrolysis temperature of cellulose was studied, as an important parameter of degradation, also related to the acidity of wood. Decreases in the pyrolysis temperature of degraded cellulose were correlated to decreases of its polymerization degree. Thermal analysis has been also used to investigate the wood de‐acidification efficacy after the treatment with alkaline nanoparticles. Hydro‐thermally aging, carried out on de‐acidified Vasa wood samples demonstrated that de‐acidification with nanoparticles facilitates protection of wood toward further acid degradation.
Innovative Plasma Processes for Consolidation of Biodeteriorated Ancient Papers
Authors: Vassallo E. , Laguardia L. , Ricci D. , Bonizzoni G.
Published: April 2006

Deterioration of paper materials is mainly due to the degradation of cellulose caused by a lot of factors such as chemical attack due to acidic hydrolysis, oxidative agent, light, air pollution and biological attack due to presence of microorganisms like bacteria and fungi. Various technologies exist to limit the degradation of the paper materials but in a few cases are unsuited or produce no good results. Plasma technology is an innovative process which can be an alternative to the conventional methods. The plasma treatment produces a synergetic result of sterilization and coating of the paper. This technology is environmentally friendly and can be used for industrial applications. The aim of this project is the increasing of the paper tensile strength and paper conservation by means of several different plasma treatments.
Wave scattering with the UV multilevel partitioning method: Three‐dimensional problem of dielectric rough‐surface scattering
Authors: Li Zhong‐Xin
Published: April 2006

A scalar wave 3D dielectric rough‐surface scattering problem solved by a UV method with multilevel partitioning (UV‐MLP) is developed in this paper. For a 3D dielectric rough‐surface scattering problem, the scattering structure is partitioned into a multilevel block. By looking up the rank in the static problem, the impedance matrix for a given transmitting and receiving block is expressed into a product of U and V matrices. The UV method is illustrated by applying a 3D scattering problem to a random dielectric rough surface in this paper. The coupled scalar integral equations for dielectric rough‐surface boundary conditions are treated. Numerical simulation results are illustrated. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1313–1317, 2006;Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.21613
Design of the band‐rejected UWB antenna with the ring‐shaped parasitic patch
Authors: Kim Ki‐Hak , Park Seong‐Ook
Published: April 2006

A novel UWB antenna with band‐elimination characteristic is presented. The proposed antenna is fed by microstrip line and consists of an inversed bell‐shape radiation patch, rounded ground, and a ring‐shaped parasitic patch. The proposed antenna utilizes a ring‐shape parasitic patch to reject the frequency band (5.15–5.825 GHz) limited by IEEE 802.11a and HIPERLAN/2. In addition, the rejected frequency band can be varied by adjusting the length and location of the ring‐shape parasitic patch. By means of a normalized antenna transfer function, both the frequency‐domain and time‐domain characteristics of the antenna are carefully investigated. The fabricated antenna can achieve broad bandwidth covering 2.2 to 11.8 GHz with VSWR below 2. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48:1310–1313, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21614
Spiral inductors fabricated on multi‐layered Bragg reflector for Si‐based RF IC applications
Authors: Mai Linh , Song Hae‐il , Minh Tuan Le , Van Su Pham , Yoon Giwan
Published: April 2006

In this paper, for the first time, a novel physical structure of planar spiral inductors fabricated on a multilayered Bragg reflector is proposed. The multilayered Bragg reflector (BR) was fabricated on Si substrate. The effects of the multilayered Bragg reflector and inductor patterns on the characteristics of inductors are studied. The results show that the inductors fabricated on the Bragg reflector result in a significant improvement in terms of the S11‐parameter. This approach seems highly feasible and promising for future Si‐based RF IC applications. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1296–1298, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21621
A Mach–Zehnder nonzero order joint transform correlator for aircraft pattern recognition
Authors: Lee Chungcheng , Chen Chulung
Published: April 2006

A Mach–Zehnder device is utilized in a nonzero‐order joint‐transform correlator system for aircraft pattern recognition. The Stokes relations, which involve the amplitudes of reflected and transmitted parts of a plane wave incident on a plane‐refracting surface, are cleverly utilized. The proposed method can directly remove the large zero‐order term in one step. The correlator also shows the advantage of the ability to detect distortion invariance. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1290–1293, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21623
Electromagnetic scattering by arbitrary shaped inhomogeneous impedance cylinder using physical optics method
Authors: Tezel Necmi Serkan , Paker Selçuk
Published: April 2006

The electromagnetic scattering problem related to an arbitrarily shaped inhomogeneous impedance cylinder is investigated using the physical optics (PO) method. In the solution, induced electric and magnetic currents on the illuminated region of the impedance surface are expressed by means of the incident field and the inhomogeneous impedance boundary condition (IBC), then the scattered field is calculated using the Huygens‐type Green's formula. Obtained scattering width (SW) results are compared with those obtained by other analytical and numeric methods and good agreements are observed, especially for the monostatic case. Because of the fact that the PO method does not need matrix inversion, which requires high CPU time, the PO method also significantly reduces the computer calculation time according the other methods. In this study, the TM case is considered, but a similar procedure can be easily applied to TE case and also 3D inhomogeneous impedance objects. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1282–1286, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21625
A new optical gigabit Ethernet network element
Authors: Silva H. J. P. P. , Mosso M. M. , Lima R. A. A. , Guedes B. C. L. , Podcameni A.
Published: April 2006

The main purpose of this work is the generation of new intelligent functionalities at the optical network physical layer in Gigabit Ethernet interfaces and nodes. These new tools are achieved by the use of a field programmable gated array (FPGA) integrated circuit associated with microwave RF subcarriers. With such intelligence, a new IP/Ethernet network element is introduced and described, and special attention is dedicated to its structure, to its implementation and to the aspects of its use in networks. An experimental setup using the developed element is shown as a proof‐of‐concept, demonstrating the characteristics of the system and the transparency of the optical intelligence with respect to the Ethernet standard. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1330–1334, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21626
Studies on the dielectric behaviour of polypyrrole and its composites with poly (vinyl chloride)
Authors: John Honey , Thomas Rinku M. , Jacob Joe , Joseph Rani , Mathew K. T.
Published: April 2006

Polypyrrole/poly (vinyl chloride) semi‐interpenetrating networks of different compositions are prepared using ammonium per sulfate initiator at room temperature in pellet form and film form and their dielectric properties are studied at different microwave frequencies. An HP 8510 Vector network analyzer interfaced with a computer is used. The cavity‐perturbation technique is employed for the study. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1324–1326, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21628
Optimum use of high‐impedance surface in PCB to mitigate the simultaneous switching noise and radiated emission
Authors: Peña‐Rivero R. , Jardón Aguilar H. , Linares y Miranda R.
Published: April 2006

Optimum use of high‐impedance surfaces (HIS) in high‐speed printed circuit boards (PCBs) of two layers to mitigate the simultaneous switching noise (SSN) and radiated emission is presented. The optimum condition is obtained with two rows of square pads between which is the power supply bus, creating a rejection over the bandwidth frequency of interest. The effective method in two‐layer PCBs with two rows (3‐mm each) of square pads is implemented with a 0.5‐mm separation between the power‐supply bus, in the 8–12‐GHz frequency range, obtaining 20‐dB rejection and 15‐dB less radiated emission. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1446–1449, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21632
A two‐pole 900/1800‐MHz microstrip filter for dual‐band applications
Authors: Guan Xuehui , Ma Zhewang , Cai Peng , Anada Tetsuo , Hagiwara Gen
Published: April 2006

A two‐pole 900/1800‐MHz dual‐band bandpass filter using microstrip open‐loop resonators is proposed. Dual‐band characteristics are obtained by using the fundamental and first spurious resonance of the resonators. Both the internal and external couplings of the filter are appropriately designed to simultaneously satisfy the dual‐band requirements. The measured filtering characteristics of the designed filter agree well with the simulated responses. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1388–1391, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21639
Analysis and selection of optimum driving current combinations for tunable wavelength laser
Authors: Lee Yang‐Han , Yang Chun‐Liang , Chuang Ming‐Hsueh , Tseng Hsien‐Wei , Chou Yung‐Shan , Tsao Hen‐Wai , Lee San‐Liang
Published: April 2006

In a distributed Bragg reflector (DBR) laser, driving currents in the tri‐electrode are adjusted to generate various channels in the ITU‐Band. Many driving‐current combinations can generate the same ITU channel. But when we take system performance into consideration, such as the chirping and the switching time when we switch DBR lasers between ITU channels, certain current combinations will generate better system performance than the others. In this paper, we develop the principle of how to select current combinations in order to obtain better system performance and also discuss the method of how to evaluate the system performance when different current combinations are selected. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1417–1423, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21643
A method to simultaneously extract the small‐signal equivalent circuit and noise parameters of heterojunction bipolar transistors
Authors: Maya Ma. Carmen , Lázaro Antonio , Pradell Lluís
Published: April 2006

A method to extract the elements of the small‐signal equivalent circuit and the noise parameters (NPs) of heterojunction bipolar transistors (HBTs) is presented. The extraction is done by simultaneous fitting of the measured S‐parameters, noise figure (for a well‐matched impedance), and NPs (estimated using the so‐called F50 method). An additional error term, given by the root square sum of the differences between the NPs estimated from the F50 method and the NPs directly computed using the Hawkins model, is considered in order to avoid nonphysical results in the extraction of the intrinsic noise sources. To obtain the initial values of the equivalent‐circuit elements, analytical expressions are applied under a number of bias conditions, namely, reverse bias, forward bias, and active bias. Experimental verification of the extraction of the equivalent‐circuit elements and NPs of an HBT, up to 8 GHz, are presented, and the NPs are compared to those measured with an independent (tuner‐based) method. The behavior of Fmin, extracted using the proposed method, as a function of the HBT collector current, is also presented. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1372–1379, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21649
Wideband antenna for mobile terminals based on the handset PCB resonance
Authors: Antonino‐Daviu E. , Suarez‐Fajardo C. A. , Cabedo‐Fabrés M. , Ferrando‐Bataller M.
Published: April 2006

The resonant behavior of a handset printed circuit board (PCB) is analyzed by means of the Theory of Characteristic Modes (TCM). The information obtained is utilized to design a wideband antenna suitable for mobile terminals. To feed this resonant structure, a planar square plate is used. This antenna exhibits an excellent wideband performance and omnidirectional radiation patterns. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1408–1411, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21654
Line‐of‐Sight MIMO indoor measurements at 2.4 GHz
Authors: Ibernón‐Fernández Rubén , Molina‐García‐Pardo José‐María , Juan‐Llácer Leandro
Published: April 2006

The short‐range line‐of‐sight (LoS) multiple‐input multiple‐output (MIMO) channel transfer function is measured for a 4 × 4 system between 2.35 and 2.55 GHz for different antenna spacing and orientations in an indoor scenario. Capacity and correlation are investigated, and a mean capacity loss of 4 b/s/Hz is measured when the receiver is rotated 90°. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1403–1405, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21656
Electromagnetically‐coupled patch antenna for phased array applications for mobile satellite communications
Authors: Wang Qingyuan
Published: April 2006

An economical electronically‐scanned patch antenna array with quasi‐hemispheric coverage is under design in our laboratory for Inmarsat satellite communications. This paper reports the CAD simulation and test results of a simple‐structured, electromagnetically‐coupled patch antenna with circular polarization, for such array applications. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1279–1282, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21676
A triangular plate element for thermo‐elastic analysis of sandwich panels with a functionally graded core
Authors: Das M. , Barut A. , Madenci E. , Ambur D. R.
Published: April 2006

A sandwich construction is commonly composed of a single soft isotropic core with relatively stiff orthotropic face sheets. The stiffness of the core may be functionally graded through the thickness in order to reduce the interfacial shear stresses. In analysing sandwich panels with a functionally gradient core, the three‐dimensional conventional finite elements or elements based on the layerwise (zig‐zag) theory can be used. Although these elements accurately model a sandwich panel, they are computationally costly when the core is modelled as composed of several layers due to its grading material properties. An alternative to these elements is an element based on a single‐layer plate theory in which the weighted‐average field variablescapture the panel deformation in the thickness direction. This study presents a new triangular finite element based on {3,2}‐order single‐layer theory for modelling thick sandwich panels with or without a functionally graded core subjected to thermo‐mechanical loading. A hybrid energy functional is employed in the derivation of the element because of a C1 interelement continuity requirement. The variations of temperature and distributed loading acting on the top and bottom surfaces are non‐uniform. The temperature also varies arbitrarily through the thickness. Copyright © 2006 John Wiley & Sons, Ltd.
A numerical study of wave structures developed on the free surface of a film flowing on inclined planes and subjected to surface shear
Authors: Shuaib N. H. , Power H. , Hibberd S. , Simmons K.
Published: April 2006

In this work, we determine the different patterns of possible wave structures that can be observed on a thin film flowing on an inclined plane when at the free surface a shear force (surface traction) is applied. Different wave structures are obtained dependening on the selected combination of downstream and upstream boundary conditions and initial conditions. The resulting initial boundary value problems are solved numerically using the direct BEM numerical solution of the complete two‐dimensional Stokes system of equations. In our numerical results, the initial discontinuous shock profiles joining uniform fluid depths are smoothed due to the two‐dimensional character of the Stokes formulation, including the effect of the gravitational force as well as the interfacial surface tension force. In this way, physically feasible continuous surface profiles are determined, in which the initial uniform depths are joined by smooth moving wave structures. Numerical solutions have been attained to reproduce the different patterns of possible wave structures previously reported in the literature and extended to identify some other new structures and features defining the behaviour of the surface patterns. Copyright © 2006 John Wiley & Sons, Ltd.
On the enforcing energy conservation of time‐finite elements for particle systems
Authors: Bui Q. V.
Published: April 2006

In the framework of the time‐finite element method, energy‐conserving temporal integrators are developed through the design of non‐standard quadrature. The latter can be achieved by a global enforcement of the force field issued from the standard quadrature. This might, however, lead to an undesirable coupling of all degrees of freedom. A local enforcement is suggested to enhance the enforcement of energy conservation through a tailored modification to each component of acting forces. Representative examples for non‐linear particle systems are presented in order to examine the quality of various approaches in the enforcement of energy conservation. Copyright © 2006 John Wiley & Sons, Ltd.
Scale‐related topology optimization of cellular materials and structures
Authors: Zhang Weihong , Sun Shiping
Published: April 2006

The integrated optimization of lightweight cellular materials and structures are discussed in this paper. By analysing the basic features of such a two‐scale problem, it is shown that the optimal solution strongly depends upon the scale effect modelling of the periodic microstructure of material unit cell (MUC), i.e. the so‐called representative volume element (RVE). However, with the asymptotic homogenization method used widely in actual topology optimization procedure, effective material properties predicted can give rise to limit values depending upon only volume fractions of solid phases, properties and spatial distribution of constituents in the microstructure regardless of scale effect. From this consideration, we propose the design element (DE) concept being able to deal with conventional designs of materials and structures in a unified way. By changing the scale and aspect ratio of the DE, scale‐related effects of materials and structures are well revealed and distinguished in the final results of optimal design patterns. To illustrate the proposed approach, numerical design problems of 2D layered structures with cellular core are investigated. Copyright © 2006 John Wiley & Sons, Ltd.
Selective binding and enrichment for low‐molecular weight biomarker molecules in human plasma after exposure to nanoporous silica particles
Authors: Terracciano Rosa , Gaspari Marco , Testa Flaviano , Pasqua Luigi , Tagliaferri Pierosandro , Cheng Mark Ming‐Cheng , Nijdam A. Jasper , Petricoin Emanuel F. , Liotta Lance A. , Cuda Giovanni , Ferrari Mauro , Venuta Salvatore
Published: April 2006

The present manuscript describes a biomarker capturing strategy based on nanoporous silica particles. The method is shown to enrich the yield of species in the low‐molecular weight proteome (LMWP), allowing detection of small peptides in the low‐nanomolar range. Plasma samples were exposed to the silica particles, and the captured molecular species were profiled using MALDI‐TOF. Mass spectra of the silica‐treated human plasma samples showed a significant enrichment in MALDI‐TOF protein profiles in the LMWP. Preliminary results indicated good level of reproducibility in plasma profiles with CVs on peak heights ranging from 6.3 to 14.7%. The MALDI‐TOF signature changed significantly when the characteristics of the nanoporous silica were altered. The facile sample pretreatment before MS analysis, coupled to the potential for tailoring the surface properties of silica supports, hold promise for improving the recovery of low‐abundance serum biomarkers.
Preparation of SiO2/PMMA composite particles via conventional emulsion polymerization
Authors: Cheng Xinjian , Chen Min , Zhou Shuxue , Wu Limin
Published: April 2006

A series of SiO2/PMMA composite particles with different morphologies were prepared by conventional emulsion polymerization by the aid of acid–base interaction between the silanol groups of unmodified silica particles and the amino groups of 4‐vinylpyridine. In this approach, no surface treatment for nanosilica particles was required. The morphologies of composite particles, for example, multicore–shell, raspberry‐like, and conventional core–shell, could be controlled by modulating emulsifier content, monomer/silica ratio, silica size, and monomer feed method. The possible particle formation mechanisms were discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3807–3816, 2006
Optimization strategies for segmented Peltier coolers
Authors: Müller Eckhard , Walczak Steven , Seifert Wolfgang
Published: April 2006

Commercialisation of Peltier coolers has progressed during last years and special efforts have been undertaken to enhance the efficiency of thermoelectric (TE) devices. Along with the continued search for advanced TE materials, the concept of functionally graded materials (FGM) offers a pathway to gradual improvement of device performance. Starting from the first principles of thermoelectricity in a 1D approach, a differential equation governing the coupling of thermal and electrical transports is applied here for modelling multi‐segment Peltier cooling elements within the framework of a constant parameters theory.

With the constant material properties values in each segment representing volume average values of spatially varying non‐constant profiles, this model provides an approximation of excellent accuracy also for continuously graded elements. The work presents parameter studies on segmented Peltier elements based on material parameters close to real data thus revealing strategies for optimal design. As target parameters, the maximum C.O.P., maximum cooling power, and the maximum temperature difference have been determined for various shapes of gradients. Tendencies for favourite gradients of the Seebeck coefficient and the electrical conductivity have been found. Example calculations for a material withZT≈ 1 show an enhancement of the maximum temperature difference by up to 15% (13 K). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic domain walls at the edge of patterned NiO/NiFe bilayers
Authors: Kim S. W. , Lee S. S. , Gomez R. D. , Hahn E. J. , Hwang D. G.
Published: April 2006

The magnetic domain walls at the edges of a large patterned and exchange‐biased NiO (10–60 nm)/NiFe (10 nm) bilayers and their motions with applied field were investigated by MFM. Three kinds of domain walls were found at the edges of the NiO (30 nm)/NiFe (10 nm) bilayer having the exchange biasing field (Hex) of 21 Oe. Two zigzag charged walls and Néel wall appeared at the edges perpendicular and parallel to Hex, respectively. The zigzag charged walls are nearly a factor of three wider than the Néel wall, and were not observed for the strong exchange‐biased bilayer (60 nm NiO, H ex = 75 Oe). We investigated the subsequent motion of the walls, and identified the pinning and nucleation sites during magnetization reversal. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation of inorganic–organic hybrid titania sol–gel nanocomposite films, and their dielectric properties
Authors: Kim Hoon , Pramanik Nimai Chand , Ahn Bok Yeop , Seok Sang Il
Published: April 2006

Hybrid titania materials were prepared by a process involving the phase separation of TiO2 by hydrolysis and polycondensation from hybrids between titanium tetraisopropoxide (TTIP) and 3‐(methacryloyloxy)propyl trimethoxysilane (MPTS) with excess acidic water at an elevated temperature (80 °C). The formation of TiO2 nanoparticles within the hybrid materials was studied as a function of the ageing time as well as the Ti/Si molar ratio. The crystalline phases of the TiO2 nanoparticles formed in situ within the inorganic–organic hybrid matrix were characterized by X‐ray diffraction and Fourier transform infrared studies. The microstructures and the morphologies of thick films of the hybrid materials were studied using scanning and transmission electron microscopy, which showed the existence of nanocrystalline TiO2 within the crack‐free hybrid matrix. The dielectric constants of the composites were found to be in the range 5.0–7.1, depending on the measuring frequency and the composite composition. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Role of interfaces on the direct tunneling and the inelastic tunneling behaviors through metal/alkylsilane/silicon junctions
Authors: Aswal D. K. , Petit C. , Salace G. , Guérin D. , Lenfant S. , Yakhmi J. V. , Vuillaume D.
Published: April 2006

We studied the influence of the end group of the alkylsilane molecule used in Self Assembled Monolayer (SAM) in Silicon/SAM/Metal junctions. By Inelastic Electron Tunneling spectroscopy (IETS), we showed the formation of a covalent bond between the molecules and the gold electrode in the case of a thiol terminated alkylsilane. By electrical characterizations, we demonstrated that the thiol group at the interface avoids diffusion of gold into the molecule even for a 3 carbons chain. For this short molecule, we observed pure tunnel conduction with barrier height at the monolayer/Si and monolayer/Au interfaces found to be respectively 2.14 and 2.56 eV. These values were obtained using Simmons equation with an effective mass parameter m * = 0.16m e (m e = mass of the electron).This extends the demonstration of the excellent tunnel dielectric behavior of these organic monolayers down to 3 carbon atoms with a thiol/Au bond at the interface. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of matrix defects on the photoluminescence of InAs self‐assembled quantum dots
Authors: Chahboun A. , Baidus N. V. , Demina P. B. , Zvonkov B. N. , Gomes M. J. M. , Cavaco A. , Sobolev N. A. , Carmo M. C. , Vasilevskiy M. I.
Published: April 2006

We report the effect of defects that appear during capping layer growth or are introduced intentionally, on the photoluminescence (PL) properties of InAs strained quantum dots. A treatment of the samples with CCl4 during the growth leads to the reduction of native defect concentration in the GaAs matrix. This is shown to improve the emission intensity and to remove the quenching effect at room temperature. Some samples were subjected to proton irradiation in order to generate more defects in the matrix. The comparison between the emission from as‐grown samples and irradiated ones shows a decrease of the PL intensity with the irradiation dose. However, no change in the activation energy for carrier's thermal escape was observed. The deterioration of the emission properties with the increasing irradiation dose is probably related to traps generated by the irradiation in the matrix, which reduce the overall concentration of the photocarriers. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Density functionals and half‐metallicity in La2/3Sr1/3MnO3
Authors: Ferrari V. , Pruneda J. M. , Artacho Emilio
Published: April 2006

The electronic structure and equilibrium geometry of La2/3Sr1/3MnO3 are studied theoretically by means of density functional calculations. The doping is treated by introducing holes and a compensating jellium background. The results for the local density approximation (LDA) agree with previous LDA calculations, with an equilibrium volume 5.3% too small and with both majority and minority spin states present at the Fermi level for the relaxed system. The generalised gradient approximation (GGA) offers a qualitatively improved description of the system, with a more realistic volume, and a half‐metallic behaviour for the relaxed structure, which enables studies needing theoretical relaxation. The ideal MnO2‐terminated (001) surface is then described with explicit doping. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Symmetry breaking and Wigner molecules in few‐electron quantum dots
Authors: Yannouleas Constantine , Landman Uzi
Published: April 2006

We discuss symmetry breaking in two‐dimensional quantum dots resulting from strong interelectron repulsion relative to the zero‐point kinetic energy associated with the confining potential. Such symmetry breaking leads to the emergence of crystalline arrangements of electrons in the dot. The so‐called Wigner molecules form already at field‐free conditions. The appearance of rotating Wigner molecules in circular dots under high magnetic field, and their relation to magic angular momenta and quantum‐Hall‐effect fractional fillings is also discussed. Recent calculations for two electrons in an elliptic quantum dot, using exact diagonalization and an approximate generalized‐Heitler–London treatment, show that the electrons can localize and form a molecular dimer for screened interelectron repulsion. The calculated singlet‐triplet splitting (J ) as a function of the magnetic field (B ) agrees with cotunneling measurements; its behavior reflects the effective dissociation of the dimer for large B . Knowledge of the dot shape and of J (B ) allows determination of two measures of entanglement (concurrence and von Neumann entropy for indistinguishable fermions), whose behavior correlates also with the dissociation of the dimer. The theoretical value for the concurrence at B = 0 agrees with the experimental estimates. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Charting Biological and Chemical Space: PSSC and SCONP as Guiding Principles for the Development of Compound Collections Based on Natural Product Scaffolds
Authors: Arve Lars , Voigt Tobias , Waldmann Herbert
Published: April 2006

Finding small molecules that selectively modulate protein function remains one of the major challenges in the fields of chemogenomics and drug development. Natural products interact with proteins in their biosynthesis and when displaying biological activity, and can therefore be considered as “privileged structures”. Thus, natural products may serve as biologically validated starting points for the design of focused compound collections. In recent years, effective synthesis methods for natural‐product‐based focused compound collections have been developed, including multi‐component reactions. This review discusses recent advances in the synthesis of natural‐product‐inspired compound collections as well as the application of Protein Structure Similarity Clustering (PSSC) and a Structural Classification Of Natural Products (SCONP) as guiding principles for the design of focused compound collections based on natural products.