bluuebunny/crossref_metadata_2025 huggingface dataset:
Metal–polymer nanocomposites produced by the melt‐compounding interaction of an aliphatic polyamide with metal particles
Authors: Pesetskii S. S. , Jurkowski B. , Krivoguz Y. M. , Davydov A. A. , Bogdanovich S. P.
Published: April 2007

Composites prepared at 200°C by the melt compounding of copolymer polyamide 6/66 and ferric chloride, ferric oxalate, cupric chloride, cupric formiate, cupric acetate, Cr‐carbonyl, Mo‐carbonyl, or W‐carbonyl have been studied. The solution stability and aggregation suppression for nanoparticles in a polyamide can be explained by the formation of stable polymer–metal complexes. The nitrogen atoms of amide and amine groups of polymers serve as ligands for the coordination compounds that form. The dynamic viscosity of the solutions suggests that Cr‐carbonyl forms mostly intermolecular complexes, whereas ferric oxalate, ferric chloride, cupric formiate, cupric acetate, cupric chloride, Cr‐carbonyl, Mo‐carbonyl, and W‐carbonyl form intramolecular complexes. The critical concentrations for metal‐containing compounds at which a dispersion rises to nanodimensions without aggregating in the polymer matrix under the experimental conditions are 0.024 wt % for ferric oxalate, 0.12 wt % for ferric chloride, 0.08 wt % for cupric formiate, 0.096 wt % for cupric acetate, and 0.19 wt % for cupric chloride. Metal carbonyls undergo dispersion (with their concentration up to 5 wt %) in polyamide 6/66 without aggregating into larger formations. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Preparations and properties of thermosensitive terpolymers of N‐isopropylacrylamide, sodium 2‐acrylamido‐2‐methyl‐propanesuphonate, and N‐tert‐butylacrylamide
Authors: Shao Dan , Ni Caihua
Published: April 2007

Terpolymers based on N‐isopropylacrylamide, sodium 2‐acrylamido‐2‐methyl‐propanesulfonate, and N‐tert‐butylacrylamide were synthesized by free‐radical copolymerization with 2,2′‐azobisisobutyronitrile as an initiator. The lower critical solution temperatures (LCSTs) of the linear polymer aqueous solutions were determined by the measurement of the transmittance on UV at different temperatures. The influence of the polymer concentration, polymer composition, and ionic strength on the LCSTs of the linear polymers was investigated. The LCST decreased with increases in the hydrophobic monomer N‐tert‐butylacrylamide, polymer concentration, and ionic strength. The phase transition became sharp when the polymer concentration and ionic strength increased. Meanwhile, the crosslinked hydrogels were prepared with the same recipe used for the linear terpolymers, but a crosslinker was added to the reaction system. The swelling ratios of the hydrogels at various temperatures and salt solutions were determined. The hydrogels possessed both high swelling ratios and thermosensitivity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Modification of silica gel, cellulose, and polyurethane with a sterically hindered N‐halamine moiety to produce antimicrobial activity
Authors: Barnes K. , Liang J. , Worley S. D. , Lee J. , Broughton R. M. , Huang T. S.
Published: April 2007

The sterically hindered amine monomer 4‐[3‐triethoxysilylpropoxyl]‐2,2,6,6‐tetramethylpiperidine has been synthesized and covalently bonded to the surfaces of silica gel particles and cellulose (cotton) and copolymerized in a polyurethane coating formulation. Upon exposure to dilute sodium hypochlorite (household bleach), a very stable N‐Cl bond is formed in situ at the hindered amine nitrogen site. This source of oxidative chlorine provides an antimicrobial function to the silica gel, cotton, and polyurethane. Stability, regenerability, and biocidal efficacy data are presented. The new N‐halamine materials were remarkably effective against Staphylococcus aureus and Escherichia coli O157 : H7 in brief periods of contact. The materials should find application in water treatment and medical applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Influence of processing conditions on the morphological and mechanical properties of compatibilized PP/LCP blends
Authors: Filipe Susana , Manuel Maia João , Rosa Leal Catarina , Teresa Cidade Maria
Published: April 2007

The main aim of this work is to study the influence of the application of different processing conditions on the morphological and mechanical properties of thermoplastic/LCP blends, in which the viscosity ratios are inferior to unity and decrease with increasing temperature. The way the microstructure evolves along the extruder determines the final morphology and thus, the mechanical performance of the systems. In the present case, the mechanical properties are related with the degree of fibrillation in the final composites. The best degree of fibrillation was obtained for low screw speeds and temperatures and for intermediate outputs. The use of high screw speeds and processing temperatures results in a decrease of the viscosity ratio, in the former case via an increase in the viscous dissipation, at the regions of higher shear rates (kneading‐elements). The application of a lower processing temperature is advantageous for deformation, break‐up, and fibrillar formation because of the higher viscosity ratios and higher shear stresses involved. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Toughened electrospun nanofibers from crosslinked elastomer‐thermoplastic blends
Authors: Fang Jian , Lin Tong , Tian Wendy , Sharma Arnav , Wang Xungai
Published: April 2007

A crosslink‐able elastomeric polyester urethane (PEU) was blended with a thermoplastic, polyacrylonitrile (PAN), and electrospun into nanofibers. The effects of the PEU/PAN ratio and the crosslinking reaction on the morphology and the tensile properties of the as‐spun fiber mats were investigated. With the same overall polymer concentration (9 wt %), the nanofiber containing higher composition of PEU shows a slight decrease in the average fiber diameter, but the tensile strength, the elongation at break and tensile modulus of the nanofiber mats are all improved. These tensile properties are further enhanced by slight crosslinking of the PEU component within the nanofibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Synthesis, Structure and Hypoxic Cytotoxicity of 3‐Amino‐1,2,4‐benzotriazine‐1,4‐dioxide Derivatives
Authors: Jiang Faqin , Weng Qinjie , Sheng Rong , Xia Qing , He Qiaojun , Yang Bo , Hu Yongzhou
Published: April 2007

A series of novel 3‐amino‐1,2,4‐benzotriazine‐1,4‐dioxide derivatives were synthesized and screened for their in vitro cytotoxicity against promyelocytic leukemia HL‐60, androgen‐independent prostate tumor PC3, hepatocellular carcinoma Bel‐7402, human esophagus tumor ECA‐109, and human breast tumor MCF‐7 cell lines in hypoxia and in normoxia. Most compounds showed higher cytotoxic activity both in hypoxia and in normoxia. Among them, compounds 61 and 62 showed more potent cytotoxic activity and hypoxic selectivity when compared to tirapazamine.
A measure theoretic approach to information retrieval
Authors: Dominich Sándor , Kiezer Tamás
Published: April 2007

The vector space model of information retrieval is one of the classical and widely applied retrieval models. Paradoxically, it has been characterized by a discrepancy between its formal framework and implementable form. The underlying concepts of the vector space model are mathematical terms: linear space, vector, and inner product. However, in the vector space model, the mathematical meaning of these concepts is not preserved. They are used as mere computational constructs or metaphors. Thus, the vector space model actually does not follow formally from the mathematical concepts on which it has been claimed to rest. This problem has been recognized for more than two decades, but no proper solution has emerged so far. The present article proposes a solution to this problem. First, the concept of retrieval is defined based on the mathematical measure theory. Then, retrieval is particularized using fuzzy set theory. As a result, the retrieval function is conceived as the cardinality of the intersection of two fuzzy sets. This view makes it possible to build a connection to linear spaces. It is shown that the classical and the generalized vector space models, as well as the latent semantic indexing model, gain a correct formal background with which they are consistent. At the same time it becomes clear that the inner product is not a necessary ingredient of the vector space model, and hence of Information Retrieval (IR). The Principle of Object Invariance is introduced to handle this situation. Moreover, this view makes it possible to consistently formulate new retrieval methods: in linear space with general basis, entropy‐based, and probability‐based. It is also shown that Information Retrieval may be viewed as integral calculus, and thus it gains a very compact and elegant mathematical way of writing. Also, Information Retrieval may thus be conceived as an application of mathematical measure theory.
Metal‐Ion‐Mediated Tuning of Duplex DNA Binding by Bis(2‐(2‐pyridyl)‐1H‐benzimidazole)
Authors: Bhattacharya Santanu , Chaudhuri Padmaparna
Published: April 2007

Studies of double‐stranded‐DNA binding have been performed with three isomeric bis(2‐(n‐pyridyl)‐1H‐benzimidazole)s (n=2, 3, 4). Like the well‐known Hoechst 33258, which is a bisbenzimidazole compound, these three isomers bind to the minor groove of duplex DNA. DNA binding by the three isomers was investigated in the presence of the divalent metal ions Mg2+, Co2+, Ni2+, Cu2+, and Zn2+. Ligand–DNA interactions were probed with fluorescence and circular dichroism spectroscopy. These studies revealed that the binding of the 2‐pyridyl derivative to DNA is dramatically reduced in the presence of Co2+, Ni2+, and Cu2+ ions and is abolished completely at a ligand/metal‐cation ratio of 1:1. Control experiments done with the isomeric 3‐ and 4‐pyridyl derivatives showed that their binding to DNA is unaffected by the aforementioned transition‐metal ions. The ability of 2‐(2‐pyridyl)benzimidazole to chelate metal ions and the conformational changes of the ligand associated with ion chelation probably led to such unusual binding results for the ortho isomer. The addition of ethylenediaminetetraacetic acid (EDTA) reversed the effects completely.
Bayesian State Space Models for Inferring and Predicting Temporal Gene Expression Profiles
Authors: Liang Yulan , Kelemen Arpad
Published: April 2007

Prediction of gene dynamic behavior is a challenging and important problem in genomic research while estimating the temporal correlations and non‐stationarity are the keys in this process. Unfortunately, most existing techniques used for the inclusion of the temporal correlations treat the time course as evenly distributed time intervals and use stationary models with time‐invariant settings. This is an assumption that is often violated in microarray time course data since the time course expression data are at unequal time points, where the difference in sampling times varies from minutes to days. Furthermore, the unevenly spaced short time courses with sudden changes make the prediction of genetic dynamics difficult. In this paper, we develop two types of Bayesian state space models to tackle this challenge for inferring and predicting the gene expression profiles associated with diseases. In the univariate time‐varying Bayesian state space models we treat both the stochastic transition matrix and the observation matrix time‐variant with linear setting and point out that this can easily be extended to nonlinear setting. In the multivariate Bayesian state space model we include temporal correlation structures in the covariance matrix estimations. In both models, the unevenly spaced short time courses with unseen time points are treated as hidden state variables. Bayesian approaches with various prior and hyper‐prior models with MCMC algorithms are used to estimate the model parameters and hidden variables. We apply our models to multiple tissue polygenetic affymetrix data sets. Results show that the predictions of the genomic dynamic behavior can be well captured by the proposed models. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Aromaticity in Metallabenzenes
Authors: Fernández Israel , Frenking Gernot
Published: April 2007

The electronic structure and bonding situation in 21 metallabenzenes (metal=Os, Ru, Ir, Rh, Pt, and Pd) were investigated at the DFT level (BP86/TZ2P) by using an energy decomposition analysis (EDA) of the interaction energy between various fragments. The aim of the work is to estimate the strength of the π bonding and the aromatic character of the metallacyclic compounds. Analysis of the electronic structure shows that the metallacyclic moiety has five occupied π orbitals, two with b1 symmetry and three with a2 symmetry, which describe the π‐bonding interactions. The metallabenzenes are thus 10 π‐electron systems. This holds for 16‐electron and for 18‐electron complexes. The π bonding in the metallabenzenes results mainly from the b1 contribution, but the a2 contribution is not negligible. Comparison of the π‐bonding strength in the metallacyclic compounds with acylic reference molecules indicates that metallabenzenes should be considered as aromatic compounds whose extra stabilization due to aromatic conjugation is weaker than in benzene. The calculated aromatic stabilization energies (ASEs) are between 8.7 kcal mol−1 for 13 and 37.6 kcal mol−1 for 16 which is nearly as aromatic as benzene (ASE=42.5 kcal mol−1). The classical metallabenzene model compounds 1 and 4 exhibit intermediate aromaticity with ASE values of 33.4 and 17.6 kcal mol−1. The greater stability of the 5d complexes compared with the 4d species appears not to be related to the strength of π conjugation. From the data reported here there is no apparent trend or pattern which indicates a correlation between aromatic stabilization and particular ligands, metals, coordination numbers or charge. The lower metal–C5H5 binding energy of the 4d complexes correlates rather with weaker σ‐orbital interactions.
Generation, Characterization, and Electrochemical Behavior of the Palladium–Hydride Cluster [Pd3(dppm)3(μ3‐CO)(μ3‐H)]+ (dppm=Bis(diphenylphosphinomethane)
Authors: Cugnet Cyril , Lucas Dominique , Collange Edmond , Hanquet Bernard , Vallat Alain , Mugnier Yves , Soldera Armand , Harvey Pierre D.
Published: April 2007

Addition of formate on the dicationic cluster [Pd3(dppm)3(μ3‐CO)]2+ (dppm=bis(diphenylphosphinomethane) affords quantitatively the hydride cluster [Pd3(dppm)3(μ3‐CO)(μ3‐H)]+. This new palladium–hydride cluster has been characterised by 1H NMR, 31P NMR and UV/Vis spectroscopy and MALDI‐TOF mass spectrometry. The unambiguous identification of the capping hydride was made from 2H NMR spectroscopy by using DCO2− as starting material. The mechanism of the hydride complex formation was investigated by UV/Vis stopped‐flow methods. The kinetic data are consistent with a two‐step process involving: 1) host–guest interactions between HCO2− and [Pd3(dppm)3(μ3‐CO)]2+ and 2) a reductive elimination of CO2. Two alternatives routes to the hydride complex were also examined : 1) hydride transfer from NaBH4 to [Pd3(dppm)3(μ3‐CO)]2+ and 2) electrochemical reduction of [Pd3(dppm)3(μ3‐CO)]2+ to [Pd3(dppm)3(μ3‐CO)]0 followed by an addition of one equivalent of H+. Based on cyclic voltammetry, evidence for a dual mechanism (ECE and EEC; E=electrochemical (one‐electron transfer), C=chemical (hydride dissociation)) for the two‐electron reduction of [Pd3(dppm)3(μ3‐CO)(μ3‐H)]+ to [Pd3(dppm)3(μ3‐CO)]0 is provided, corroborated by digital simulation of the experimental results. Geometry optimisations of the [Pd3(H2PCH2PH2)3(μ3‐CO)(μ3‐H)]n model clusters were performed by using DFT at the B3 LYP level. Upon one‐electron reductions, the PdPd distance increases from a formal single bond (n=+1), to partially bonding (n=0), to weak metal–metal interactions (n=−1), while the PdH bond length remains relatively the same.
Noncovalent Interactions and Internal Dynamics in Dimethoxymethane–Water
Authors: Favero Laura B. , Giuliano Barbara M. , Melandri Sonia , Maris Assimo , Caminati Walther
Published: April 2007

The millimeter‐wave absorption and Fourier transform microwave spectra of five isotopologues of the 1:1 adduct of dimethoxymethane–water have been measured in supersonic expansions. Each rotational transition appears as a quintuplet, due to the internal rotation of the two methyl groups, which are nonequivalent in the adduct. The water moiety, linked asymmetrically to dimethoxymethane, behaves as a proton donor to one of its oxygen atoms and interferes with the internal rotation of the farther methyl group through a CH⋅⋅⋅O interaction. From the analysis of the observed splittings, the V3 barriers to the internal rotation of the two methyl groups have been determined to be 6.83(8) and 6.19(8) kJ mol−1. The hydrogen bond structural parameters have been determined, the OH⋅⋅⋅O and CH⋅⋅⋅O distances being 1.93(1) and 2.78(4) Å, respectively.
Assessment of ifosfamide pharmacokinetics, toxicity, and relation to CYP3A4 activity as measured by the erythromycin breath test in patients with sarcoma
Authors: Chugh Rashmi , Wagner Thomas , Griffith Kent A. , Taylor Jeremy M.G. , Thomas Dafydd G. , Worden Francis P. , Leu Kirsten M. , Zalupski Mark M. , Baker Laurence H.
Published: April 2007

BACKGROUND.

Ifosfamide is a chemotherapeutic agent that requires cytochrome P450 3A (CYP3A) for bioactivation and metabolism. To the authors' knowledge, the correlation between dose, pharmacokinetics, CYP3A, and toxicity has not been fully evaluated. A randomized Phase II trial was performed on 22 soft tissue sarcoma patients treated with doxorubicin (60 mg/m2/cycle) and either high‐dose ifosfamide (12 g/m2/cycle) or standard‐dose ifosfamide (6 g/m2/cycle). The pharmacokinetics of ifosfamide and CYP3A measurements observed are reported.

METHODS.

Pharmacokinetic parameters for ifosfamide, 2‐dichloroethylifosfamide (2‐DCE), and 3‐dichloroethylifosfamide (3‐DCE) were collected after the first ifosfamide infusion in 13 patients. Bayesian designed limited pharmacokinetic data were collected from an additional 41 patients. The erythromycin breath test (ERMBT) was performed on 81 patients as an in vivo phenotypic assessment of CYP3A activity.

RESULTS.

Fourteen‐hour (peak) plasma levels of ifosfamide, 2‐DCE, and 3‐DCE were found to correlate strongly with the respective area under the curve (AUC) 0–24 values (r= 0.97, 0.94, and 0.95;P< .0001). Patients who experienced a grade 3–4 absolute neutrophil count (ANC), platelet, or creatinine toxicity (using the National Cancer Institute Common Toxicity Criteria [version 2]) were found to have statistically significantly higher median 14‐hour plasma levels of ifosfamide, 2‐DCE, and 3‐DCE compared with patients with grade 0–2 toxicity. ERMBT was not found to correlate with pharmacokinetic parameters of ifosfamide and metabolites or toxicity.

CONCLUSIONS.

The 14‐hour plasma level of ifosfamide, 2‐DCE, and 3‐DCE is a simple and appropriate substitute for describing the AUC of ifosfamide after 1 day of a 1‒hour to 2‐hour infusion of drug. Fourteen‐hour plasma levels of ifosfamide and metabolites are useful predictors of neutropenia, thrombocytopenia, and creatinine toxicity. ERMBT was not found to accurately correlate with ifosfamide pharmacokinetics or clinical toxicity. Cancer 2007. © 2007 American Cancer Society.
Moving forward with breast cancer prevention
Authors: Chen Wendy Y. , Rosner Bernard , Colditz Graham A.
Published: April 2007

Despite randomized controlled trial data supporting the use of selective estrogen receptor modulators (SERMs) to reduce the incidence of breast cancer, to the authors' knowledge uptake has been limited. Similar to cardiovascular risk models, the routine use of breast cancer risk prevention models in the clinical setting to identify those patients at highest risk of developing breast cancer can maximize the risk‒benefit ratio of SERMs and provide an impetus to move forward with implementing breast cancer prevention.
Method of determination of the reticulocyte age distribution from flow cytometry count by a structured‐population model
Authors: Wiczling Paweł , Krzyzanski Wojciech
Published: April 2007

Background:

A flow cytometry count of reticulocytes (RET) provides information about distribution of signal emitted by reticulocyte RNA. A new method of determination of the RNA degradation rate in RET is provided. This technique allows one to determinate the age distribution of RET.

Methods:

The method is based on a series of flow cytometry counts of cultured RET. From those counts, the changes of signal distribution of RET over time are obtained. The RNA degradation rate of individual RET is then resolved based on changes in the signal distribution of the whole population of cells. The obtained relation between signal and age allows obtaining a RET age density that can be used to characterize RET age distribution and age dependence of processes that control the population dynamics.

Results:

The total maturation time of RET in rats is 3 days. The median time that a homeostatic RET spends in blood or before it becomes a mature RBC is about 0.6 days, whereas a stress RET needs 0.8 days.

Conclusions:

The proposed method provides means for studies in vivo RET dynamics using age‐structured models. © 2007 International Society for Analytical Cytology
Efficient selection of silenced primary cells by flow cytometry
Authors: Martínez‐Ferrandis José I. , Soriano Miguel A. , Martínez‐Romero Alicia , Herrera Guadalupe , Cervantes Andrés , O'Connor José‐E. , Knecht Erwin , Armengod M.‐Eugenia
Published: April 2007

Background:

RNA interference has emerged as a new and potent tool to knockdown the expression of target genes and to investigate their functions. For short time experiments with mammalian cell lines, RNA interference is typically induced by transfecting small interfering RNAs (siRNAs). Primary cells constitute important experimental systems in many studies because of their similarity to their in vivo counterparts; however, transfection of these cells has been found to be difficult. As a consequence, RNA interference of primary cells may result in mixed phenotypes because of the simultaneous presence in the same preparation of transfected and nontransfected cells. This may be particularly inconvenient when certain experiments (for example, biochemical analysis) should be performed.

Methods:

We use fluorescently labeled siRNAs to induce RNA interference in fibroblasts, and flow‐cytometry associated cell sorting to separate subpopulations of transfected cells according to fluorescence intensity.

Results:

Flow cytometry allows one to discriminate between strongly‐ and weakly‐ or nonsilenced fibroblasts, since the fluorescence intensity of transfected cells is related to the number of internalized siRNA copies and to the mRNA knockdown efficiency.

Conclusions:

The use of fluorescently labeled siRNAs may allow one to isolate by flow‐cytometry associated cell sorting the most efficiently silenced primary cells for subsequent analysis. © 2007 International Society for Analytical Cytology
Does muscular weakness account for younger children's enhanced force variability?
Authors: Sosnoff Jacob J. , Deutsch Katherine M. , Newell Karl M.
Published: April 2007

This study examined the degree to which younger children's greater variability in force control is associated with muscular weakness. Children aged 6, 8, and 10 years and adults aged 18–22 years produced isometric force via index finger metacaro‐phalangeal joint flexion to varying force levels (5%, 15%, 25%, and 35% maximal voluntary contraction). The force output of the younger children was more variable and had greater time dependent structure compared to that of the adults at all force levels. However, the effect of age on variability was significantly reduced, but not eliminated when absolute muscular strength was taken into account. It is concluded that age‐related changes in children's force control result from a multitude of developmental processes including increases in muscular strength. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 399–405, 2007.
Fine‐tuning of social play in juvenile lowland gorillas (gorilla gorilla gorilla)
Authors: Palagi Elisabetta , Antonacci Daniela , Cordoni Giada
Published: April 2007

Social play, which involves cooperation, communication, and learning, may represent a suitable field for the investigation of cognitive ability in a given species. We collected data on a captive group of gorillas in order to evaluate the potential cognitive skill of juveniles in fine‐tuning play behavior. This study revealed that juvenile gorillas are able to “place” the play session in a proper spatial/temporal context, thus evaluating a complex net of factors (e.g., play partner, play roughness, group activity, space availability). When animals play fight, they use patterns of agonistic functional contexts. Since these actions are not intrinsically different from their “serious” context, it may be hard to distinguish them. One of the most important function of play in the ontogeny of primate social cognition may be to recognize stimuli, which may indicate the intentions of conspecifics. Accordingly, we found that juvenile gorillas are able to use play signals appropriately when a clear statement of purpose is necessary (i.e., during male–male competitive play sessions and when the escape opportunities are limited). The ability to interpret such ambiguous features of social signaling could represent a central issue in the evolution of behavioral flexibility and intelligence in primates. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 433–445, 2007.
Utilizing nonlinear behavior of microbubbles in medical ultrasound
Authors: Umemura Shin‐Ichiro , Kawabata Ken‐Ichi , Sasaki Kazuaki
Published: April 2007

Microbubbles exposed to ultrasound exhibit extremely nonlinear conspicuous behaviors. Medical imaging makes wide use of the pulse inversion method, in which only this nonlinear component is extracted by adding the received signals obtained by sending the phase inverted ultrasonic pulses twice. Further, there have been research efforts to use this nonlinear behavior for sonochemical healing of tumors by the efficient generation of acoustic cavitation by illumination with the second harmonic superimposed on the fundamental wave. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(8): 63–69, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20259
The construction of periodically time‐variant convolutional codes using binary linear block codes
Authors: Ogasahara Naonori , Kobayashi Manabu , Hirasawa Shigeichi
Published: April 2007

In 1996 Rosenthal and York proposed (time‐invariant) BCH convolutional codes [4] in which the parity check matrix of a BCH code is used in the construction of the convolutional code. The lower bound on the minimum free distance of a BCH convolutional code is guaranteed by the BCH limit. In this paper we propose a periodically time‐variant convolutional code that can be constructed not only using the BCH parity check matrix but using the check matrix of any binary linear block code and show that the lower bound on the minimum free distance is guaranteed by the minimum free distance of the binary linear block code. In addition, taking 12 binary linear block codes as examples, we perform comparisons of the proposed codes with BCH convolutional codes using three evaluation criteria (minimum free distance, number of delay elements, coding rate) and show that there exist proposed codes that are superior to existing ones. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(9): 31– 40, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20271
Neuro‐hardware for peak power reduction of oversampled OFDM signal
Authors: Mori Atsushi , Ohta Masaya , Yamashita Katsumi
Published: April 2007

OFDM communication system has recently been attracting attention because of its features of high spectrum efficiency and robustness in a multipath environment. The OFDM signal often exhibits a high peak power. It is important to reduce the peak power, since communication quality is degraded and unnecessary outband power radiation is produced when such a signal is amplified by a nonlinear amplifier. This paper considers the peak power suppression problem in an oversampled OFDM signal and presents a solution using a mutually coupled neural network. The peak power suppression performance of the proposed method and the accompanying reduction of the outband radiation power and the bit error rate are evaluated by numerical experiments. Neuro‐hardware which can handle the peak power suppression process in real time is experimentally constructed, and its performance is evaluated. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(8): 54– 62, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20285
Fast aperiodic correlation algorithm for real‐valued shift‐orthogonal finite‐length sequence of length 2ν+1
Authors: Tanada Yoshihiro , Matsumoto Takahiro
Published: April 2007

Real‐valued shift‐orthogonal finite‐length sequences are sequences in which the side lobes of the aperiodic autocorrelation function become 0, except for the endpoints of the shift to both sides, and can be applied in pulse compression radar and spread spectrum communications. In this paper, a fast correlation algorithm for efficiently calculating the periodic correlation function is discussed for real‐valued shift‐orthogonal finite‐length sequences with lengthM=2ν+1. For input data, including a real‐valued shift‐orthogonal finite‐length sequence over a certain range, the value of the aperiodic correlation function is found in a certain shift range. Based on the synthesis of this sequence by the convolution of ν+1 partial sequences, the correlation processing is broken down into correlation processing of the ν+1 stages of partial sequences. As a result, the number of multiplications and the number of additions can be suppressed on the orderMlog2M. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(9): 18– 30, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20301
Secret information distribution
Authors: Okamoto Manabu , Tanaka Yoshiaki
Published: April 2007

The distribution of secret information so that no one knows which information is being passed to whom, such as in a poker game or the like, is an important issue for security. Secret information distribution is expected to have applications in key distribution, electronic voting, and so on. A secret information distribution method must maintain the secrecy and untraceability of the distributed content, without requiring any effort on the part of the recipient. In this paper, the authors propose a distribution method, using third‐party organizations, in which the recipient can easily receive the distribution without having to engage in any of the distribution work itself; the distribution work can be divided among any number of third‐party organizations in order to diffuse the danger, and thus untraceability and secrecy are maintained so long as there is no collusion or fraud among all the organizations. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(8): 9– 17, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20308
Overfitting of boosting and regularized Boosting algorithms
Authors: Onoda Takashi
Published: April 2007

The impressive generalization capacity of AdaBoost has been explained using the concept of a margin introduced in the context of support vector machines. However, this ability to generalize is limited to cases where the data does not include misclassification errors or significant amounts of noise. In addition, the research of Schapire and colleagues has served to provide theoretical support for these results from the perspective of improving margins. In this paper we propose a set of new algorithms, AdaBoostReg,ν‐Arc, and ν‐Boost, that attempt to avoid the overfitting that can occur with AdaBoost by introducing a normalization term into the objective function minimized by AdaBoost. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(9): 69– 78, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20344
Evaluation of low‐quality images and imaging enhancement methods for fingerprint verification
Authors: Takeuchi Hideyo , Umezaki Taizo , Matsumoto Noriyuki , Hirabayashi Katsumi
Published: April 2007

A serious problem of fingerprint verification devices which are easily available on the market is how to handle ‘‘dry fingers,’’ which make the reading of fingerprints difficult and often result in incorrect verification. Dry fingers are frequently observed in the elderly and in housewives who are frequently engaged in wet work. In these cases, the observed fingerprint tends to become an eroded fingerprint image, with disconnected ridges. This paper proposes a method of handling eroded fingerprint images in which such images that will result in incorrect verification are automatically identified and the ridges are recovered rapidly. First, a method for image quality evaluation that consists of evaluating the noise in the fingerprint image is discussed and the effectiveness of the method is demonstrated. Then, simple ridge recovery is performed by using edge emphasis for images which are automatically judged to be eroded fingerprints. In the experiment, a fingerprint database was acquired in winter, when dry fingers are common. The acceptance rate for the right person (recognition rate) is found to be 94.8% when the rejection rate for other persons is set as 99.99%. When the ridges are recovered in fingerprint images whose quality is judged to be low by the image evaluation measure proposed in this paper, the recognition rate is improved to 96.2%. Furthermore, when tolerance to dry fingers is considered and verification is not performed for low‐quality image judged to be difficult to recover, the recognition rate is improved to 97.2%. In environments in which few users have dry fingers, the recognition rate will be improved to 98.8% when the rejection rate for other persons is set as 99.99%. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(10): 40– 53, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20345
Metallated Phthalocyanines as the Core of Dendrimers – Synthesis and Spectroscopic Studies
Authors: Leclaire Julien , Dagiral Rodolphe , Pla‐Quintana Anna , Caminade Anne‐Marie , Majoral Jean‐Pierre
Published: April 2007

The complexation of a first‐generation dendrimer possessing a metal‐free octasubstituted phthalocyanine as its core has been carried out with copper and cobalt chlorides. In the case of the cobalt complex, the synthesis of the dendrimer has been pursued up to the eighth generation. The progressive influence of the branches upon the core has been studied with dendrimers from generation 1 to generation 7, using UV/Vis spectroscopy. These data indicate a progressive isolation of the core.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Coupling Reactions of an Allenylcarbene Complex with Alkynes and Styrene
Authors: Wen Ting Bin , Hung Wai Yiu , Sung Herman H.‐Y. , Zhou Zhongyuan , Williams Ian D. , Jia Guochen
Published: April 2007

The allenylcarbene complex [OsCl2{=CPh(η2‐CH=C=CHPh)}(PPh3)2] undergoes coupling reactions with HC≡CSiMe3 and PhC≡CC≡CPh to produce the fulvene complexes [OsCl2{η6‐C5H2(Ph)(SiMe3)(=CHPh)}(PPh3)] and [OsCl2{η6‐C5H(Ph)2(C≡CPh)(=CHPh)}(PPh3)], respectively. A similar coupling reaction also occurs between [OsCl2{=CPh(η2‐CH=C=CHPh)}(PPh3)2] and styrene.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
A Critical Review of Electronic Effects in Enediamido and α‐Diimino Complexes of the Group 4 Metals
Authors: Mealli Carlo , Ienco Andrea , Phillips Andrew D. , Galindo Agustín
Published: April 2007

The α‐diimino chelating ligand 1,4‐diaza‐1,3‐butadiene, or its dianionic enediamido form (generically defined as DAD), forms a variety of complexes with group 4 transition metals either with or without other co‐ligands. The known species are either pseudo‐octahedral [L4M(DAD)] or tetracoordinate [L2M(DAD)] with a lower degree of metal saturation in the latter case. Additionally, there are a number of known CpMLnspecies and homoleptic complexes with the formula [M(DAD)3] or [M(DAD)2]. The M‐DAD metallacycle is generally either planar or folded at the N···N vector, the latter arrangement being observed when the number of co‐ligands is reduced and hence there is insufficient saturation at the metal. The conformation also depends on the relative electron population of DAD, which is anoninnocentligand and exists as a continuum between the neutral and dianionic resonance forms. Herein some theoretical concepts, that have previously been developed to describe the bonding capabilities of DAD toward different triads of transition metals, are extended to complexes of the group 4 metals. New electronic aspects of the [M(DAD)3] complexes are described together with a completely new analysis of the [M(DAD)2] complexes. These exhibit the planar/bent conformational dichotomy, which may have an electronic and/or steric origin as it is affected by the type of substituent at the nitrogen atoms. A reasonable justification of the observed conformational preferences is found from a combination of density functional and QTAIM analyses. The latter clearly demonstrates that a peculiar intramolecular hydrogen bonding can contribute to the stabilization of planar‐type structures.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
A Quantitative Investigation of the Water‐Solubilizing Properties of Branched Oligoglycerols
Authors: Nemoto Hisao , Araki Takaaki , Kamiya Masaki , Kawamura Tomoyuki , Hino Tomoaki
Published: April 2007

Water solubility and partition‐coefficient measurements have been conducted on already known monobenzoylated octamethylenediamine‐containing branched oligoglycerols. A new oligoglycerol, a hexamer bearing eight primary hydroxy groups, has also been prepared and its properties examined. Water solubility was found to increase in an approximately geometric progression with the number of hydroxy groups and the water solubility of the hexamer derivative was atleast half a million times greater than that of the propanamide derivative. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Silver‐Catalyzed Incorporation of Carbon Dioxide into Propargylic Alcohols
Authors: Yamada Wataru , Sugawara Yudai , Cheng Hau Man , Ikeno Taketo , Yamada Tohru
Published: April 2007

The combined use of a catalytic amount of silver acetate and a stoichiometric amount of DBU efficiently catalyzed the incorporation of CO2 under mild reaction conditions into a wide range of propargylic alcohols bearing a terminal or an internal triple bond to afford the corresponding cyclic carbonates in high‐to‐excellent yields. All the cyclic carbonates obtained from the reaction were found to be single isomers. The geometries were determined to be (Z) by X‐ray crystal structure analysis and NOE experiments.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Optimization of CEC for simultaneous determination of eleven nucleosides and nucleobases in Cordyceps using central composite design
Authors: Yang Feng Q. , Li Shaoping , Li Peng , Wang Yi T.
Published: April 2007

A CEC method is described for the simultaneous determination of 11 nucleosides and nucleobases including cytosine, uracil, uridine, hypoxanthine, 2′‐deoxyuridine, inosine, guanosine, thymidine, adenine, adenosine, and cordycepin in Cordyceps using 5‐chlorocytosine arabinoside as internal standard (IS). Chemometric optimization based on central composite design was employed to find the optimum conditions. The factors for optimization were defined as three parameters: voltage, pH, and concentration of ACN as organic modifier. The resolution (Rs) between inosine and guanosine, as well as the entire run time were employed to evaluate the response function. A running buffer composed of 4 mM ammonium acetate and 2 mM triethylamine (TEA) adjusted to pH 5.3 using acetic acid, and containing 3% ACN as modifier, with gradient voltage (0–4 min: 20 kV, 4–12 min: linear gradient from 20 to 30 kV; 12–16 min: 30 kV) were found to be the optimum conditions for the separation. Separation of the 11 investigated compounds and 5‐chlorocytosine arabinoside was achieved within 16 min. The contents of the 11 compounds in natural and cultured Cordyceps sinensis, and cultured Cordyceps militaris were also compared. The result showed that CEC is an efficient method for analysis of nucleosides and nucleobases in Cordyceps, which is helpful to control the quality of this valued traditional Chinese medicine.
Two‐chiral‐component microemulsion electrokinetic chromatography–chiral surfactant and chiral oil: Part 1. Dibutyl tartrate
Authors: Kahle Kimberly A. , Foley Joe P.
Published: April 2007

The first simultaneous use of a chiral surfactant and a chiral oil for microemulsion EKC (MEEKC) is reported. Six stereochemical combinations of dodecoxycarbonylvaline (DDCV: R, S, or racemic, 2.00% w/v), racemic 2‐hexanol (1.65% v/v), and dibutyl tartrate (D, L, or racemic, 1.23% v/v) were examined as chiral pseudostationary phases (PSPs) for the separation of six pairs of pharmaceutical enantiomers: pseudoephedrine, ephedrine, N‐methyl ephedrine, metoprolol, synephrine, and atenolol. Subtle differences were observed for three chromatographic figures of merit (αenant, αmeth, k) among the chiral microemulsions; a moderate difference was observed for efficiency (N) and elution range. Dual‐chirality microemulsions provided both the largest and smallest enantioselectivities, due to small positive and negative synergies between the chiral microemulsion components. For the ephedrine family of compounds, dual‐chiral microemulsions with surfactant and oil in opposite stereochemical configurations provided higher enantioselectivities than the single‐chiral component microemulsion (RXX), whereas dual‐chiral microemulsions with surfactant and oil in the same stereochemical configurations provided lower enantioselectivities than RXX. Slight to moderate enantioselective synergies were confirmed using a thermodynamic model. Efficiencies observed with microemulsions comprised of racemic dibutyl tartrate or dibutyl‐D‐tartrate were significantly higher than those obtained with dibutyl‐L‐tartrate, with an average difference in plate count of about 25 000. Finally, one two‐chiral‐component microemulsion (RXS) provided significantly better resolution than the remaining one‐ and two‐chiral‐component microemulsions for the ephedrine‐based compounds, but only slightly better or equivalent resolution for non‐ephedrine compounds.
A critical path method for the estimation of service restoration time in power distribution systems
Authors: Lakshminarayana C. , Mohan M. R.
Published: April 2007

Distribution systems (DSs) are invariably subjected to various types of faults, causing power blackouts to occur. Distribution Engineers have the main responsibility to minimizing the duration of these power blackouts. This minimization can be achieved by the detailed study of pre‐fault load condition of the DS, isolating the faulted section, and restoring the supply to healthy sections of the DS. Hence the estimation of service restoration time (SRT) is very important in electrical distribution systems (EDS). The estimation of SRT requires detailed knowledge of the commencement time of the emergency diesel generator (EDG) in EDS and also the operating time of the various relays in EDS. This paper introduces a new concept of optimistic time (OT), pessimistic time (PT), and most likely time (MT) of starting of the EDGs in addition to the OT, PT, and MT of the operation of the relays. The proposed concept is tested on 14‐bus, 17‐bus, and 29‐bus distribution networks. The results reveal that it is highly suitable technique for the estimation of SRT under abnormal conditions. Hence this technique can easily be improved in distribution automation/service restoration algorithms. Copyright © 2007 John Wiley & Sons, Ltd.
Low complexity successive interference cancellation for MIMO–OFDM systems
Authors: Wübben Dirk , Kammeyer Karl‐Dirk
Published: April 2007

Layered architectures like the V‐BLAST scheme are a promising candidate to exploit the capacity advantages of multiple antenna systems leading to practical wireless communication schemes with very high data rates. The combination with orthogonal frequency division multiplexing (OFDM), called MIMO–OFDM, with per‐antenna‐coding is one of the most likely implementations of these multilayer architectures in frequency selective environments. In this paper, we present a novel, computational efficient implementation of successive interference cancellation (SIC) for coded MIMO–OFDM. It utilises a parallelised version of the Sorted QR Decomposition (SQRD) to achieve the same optimised detection order for all subcarriers, in order to exploit the error correction capability of the forward error correction code within the SIC. In comparison to other schemes known from literature, our approach requires only a fraction of computational complexity with almost the same performance. Copyright © 2007 John Wiley & Sons, Ltd.
Signal representation and approximation–fundamental limits
Authors: Boche Holger , Pohl Volker
Published: April 2007

The expansion of functions in orthonormal bases is an important analytical and practical instrument in many different areas such as in signal processing, in system and information theory and in communications. However, the selection of an optimal basis is a non‐trivial task in general and depends strongly on the performance measure of the concrete problem. This paper considers the basis selection problem for three different applications, starting with a problem from system theory, looking on entropy based methods from information theory, and finally it investigates the peak‐to‐average power ratio problem in communication systems. In particular, it is investigated under which conditions the problems are solvable, that is under which conditions there exists an appropriate basis. Copyright © 2007 John Wiley & Sons, Ltd.
Performance analysis of multi‐step power control algorithm for cellular systems
Authors: Chen Young‐Long , Li Chih‐Peng , Wang Jyu‐Wei , Wen Jyh‐Horng
Published: April 2007

A distributed multi‐step power control algorithm is proposed for cellular networks. The proposed scheme utilises local information to feedback control commands for power adjustments. The sufficient condition that ensures system stability is obtained. In addition, a general formula for the bound of the received CIR is derived in the presence of short‐term fading. The bound of the received CIR is shown to be a function of the number of power control steps, the step size and the dead factor. In addition, system stability for the mode‐1 power control scheme is analysed by applying the results obtained for the multi‐step power control algorithm. Furthermore, the convergence region of the received CIR for long‐term fading channels is treated as a special case by assuming that all link gains are constant for consecutive measurements. Simulation results were obtained to verify the theoretical derivations. The time required to converge on the target CIR was also analysed by simulation experiments. To demonstrate the applicability of the proposed algorithm on practical and imperfect situations, the effects of step size, power adjustment rate, feedback delay, feedback error and CIR estimation error are investigated and results substantiate the validity of our proposed algorithm. Copyright © 2007 John Wiley & Sons, Ltd.