bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carrier‐Mediated Transport of Toxic Heavy Metal Ions in Bulk Liquid Membranes
Authors: Brinchi Lucia , Germani Raimondo , Mancini Maria Vincenza , Savelli Gianfranco , Spreti Nicoletta 
Published: March 2004

AbstractTransport through a dichloromethane liquid membrane has been studied to investigate the ability of 1,1,7,7‐tetraethyl‐4‐tetradecyldiethylenetriamine (TE14DT), previously tested for the transport of copper, to act as a carrier for toxic heavy metal ions such as Cd2+, Pb2+ and Hg2+. The carrier displayed a remarkable capability to extract all the metal ions from the source to the organic phases but only cadmium was efficiently transported across the membrane. The experimental conditions optimised for the transport of copper are inadequate for lead and mercury. In fact, the inefficacy of their transport could be due, as regards lead, to the slow diffusion of the complex through the membrane, while mercury remained in the organic phase because of the high stability of the mercury‐carrier complex. Selectivity tests using binary mixtures of the metal ions showed TE14DT’s capability to transport copper or cadmium also in the presence of lead in the source phase. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis and Enantioselective Gas Chromatography of Stereoisomers of 7,11‐Dimethylheptadecane − A Pheromone Component of Lambdina Species
Authors: Chow Sharon , Koenig Wilfried A. , Kitching William 
Published: March 2004

AbstractThe stereoisomers of 7,11‐dimethylheptadecane exhibit a useful level of separation under enantioselective gas chromatographic conditions, using a modified cyclodextrin phase. Synthesis of the (7R,11R) isomer and coinjection studies establish the order of elution as (7S,11S), (7R,11R), and finally the meso form, the latter being a sex‐pheromone component of Lambdina species. Enantiomeric assays of natural samples containing this hydrocarbon system will now be possible. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of a 2,3‐Di‐O‐substituted Heptose Structure by Regioselective 3‐O‐Silylation of a 2‐O‐Substituted Heptose Derivative
Authors: Ishii Kazuyuki , Esumi Yasuaki , Iwasaki Youhei , Yamasaki Ryohei 
Published: March 2004

AbstractA 3,4‐diol derivative of 2‐O‐benzyl (Bn) heptose (Hep), methyl 6,7‐di‐O‐acetyl‐2‐O‐benzyl‐L‐glycero‐α‐D‐manno‐heptopyranoside (3), was treated with both triethylsilyl (TES) andtert‐butyldimethylsilyl (TBDMS) chlorides to regioselectively form the 3‐O‐silyl ethers4and6, respectively. To examine whether silylation of the 3,4‐diol of a 2‐O‐substituted disaccharide also gives the corresponding 3‐O‐silylated disaccharide, we synthesized α‐GlcN3‐(1⇄2)‐Hep11aby coupling a Hep 2‐OH acceptor9with a GlcN3trichloroacetimidate10. As expected from the results obtained using the 2‐O‐Bn Hep3, treatment of α‐GlcN3‐(1⇄2)‐Hep‐3,4‐diol14with TESCl followed by acetylation gave only the 3‐O‐TES15. Compound14was converted into the 3‐OH acceptor16by silylation/acetylation — without isolating15— and subsequent acid hydrolysis. By coupling the disaccharide 3‐OH acceptor16with per‐O‐benzylated β‐lactosyl trichloroacetimidate17, we obtained the desired 2,3‐branched tetrasaccharide, α‐Lac‐(1⇄3)‐[α‐GlcN3‐(1⇄2)]‐Hep18a. Hydrogenation of18a, followed byN‐acetylation, gave α‐Lac‐(1⇄3)‐[α‐GlcNAc‐(1⇄2)]‐Hep22. Thus, we synthesized the 2,3‐dibranched Hep by utilizing the 2‐O‐substituted Hep. This regioselectiveO‐3‐silylation of the 2‐O‐substituted Hep provides an intermediate that can be utilized for the synthesis of not only 2,3‐ and 3,4‐dibranched Hep but also the 2,3,4‐tribranched Hep structures present in lipooligo‐ and lipopolysaccharides produced by pathogenic Gram‐negative bacteria. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The Stereoselective Synthesis of Alkenyl‐β‐lactams by Palladium‐Catalyzed [2+2] Carbonylative Cycloaddition
Authors: Troisi Luigino , De Vitis Luisella , Granito Catia , Epifani Erbana 
Published: March 2004

AbstractAllyl halides of different structures, under CO pressure, in the presence of Et3N, a catalytic amount of Pd(OAc)2, and triphenylphosphane as ligand, undergo a [2+2] cycloaddition reaction with various imines. The reaction is highly regio‐ and stereoselective: β‐lactams are formed in good yields and with trans diastereoselectivity in both the β‐lactam ring and the vinylic moiety. New and important information is suggested regarding the known reaction mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Reactivity of β‐Carbolines and Cyclopenta[b]indolones Prepared from the Intramolecular Cyclization of 5(4H)‐Oxazolones Derived from L‐Tryptophan
Authors: Condie Glenn C. , Bergman Jan 
Published: March 2004

Abstract4‐(1H‐Indol‐3‐ylmethyl)‐2‐trichloromethyl‐1,3‐oxazol‐5(4H)‐one (4) was shown to undergo an intramolecular reaction in the presence of TFA, to afford a β‐carboline 5 and a cyclopenta[b]indolone 6 by nucleophilic addition at C‐2 and C‐5, respectively. The distribution of these two products was found to be dependent on the reaction temperature, with lower temperatures favouring the formation of the β‐carboline 5. Subsequent reactions performed on the β‐carboline 5 led to the formation of canthine and canthin‐6‐one derivatives. These syntheses both involved methyl 1‐formyl‐β‐carboline‐3‐carboxylate (20), a useful precursor which was prepared in 54% yield, by a four‐step procedure, from readily available L‐tryptophan. The cyclopenta[b]indolone 6 readily underwent oxidative deamidation to afford cyclopenta[b]indole‐2,3‐dione (37), while substitution by alcohols afforded the alkoxy derivatives 40 and 41. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
1‐(Phenylethynyl)pyrene and 9,10‐Bis(phenylethynyl)anthracene, Useful Fluorescent Dyes for DNA Labeling: Excimer Formation and Energy Transfer
Authors: Malakhov Andrei D. , Skorobogatyi Mikhail V. , Prokhorenko Igor A. , Gontarev Sergei V. , Kozhich Dmitry T. , Stetsenko Dmitry A. , Stepanova Irina A. , Shenkarev Zakhar O. , Berlin Yuri A. , Korshun Vladimir A. 
Published: March 2004

AbstractA series of novel modifying reagents, including phosphoramidites and solid supports, have been synthesized, and used for the introduction of 1‐(phenylethynyl)pyrene (PEPy) and 9,10‐bis(phenylethynyl)anthracene (BPEA) fluorescent dyes into predetermined positions of synthetic oligonucleotides. These two fluorophores have been shown to constitute an energy donor−acceptor pair, and can be used as such in fluorescent oligonucleotide probes, designed for the detection and structural studies of nucleic acids. The sensitivity of the probe to duplex formation is demonstrated. The formation of the PEPy and BPEA excimers is reported for the first time on nucleic acids. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
cycloSaligenyl‐mannose‐1‐monophosphates as a New Strategy in CDG‐Ia Therapy: Hydrolysis, Mechanistic Insights and Biological Activity
Authors: Muus Ulrike , Kranz Christian , Marquardt Thorsten , Meier Chris 
Published: March 2004

AbstractPhosphomannomutase 2 (PMM‐2) deficiency leads to an inefficient intracellular formation of mannose‐1‐phosphate (1), which causes an inherited metabolic disease with multisystemic abnormalities (Congenital Disorder of Glycosylation type Ia, CDG‐Ia). In order to circumvent this metabolic deficiency, the cycloSal approach was applied for the intracellular delivery of mannose‐1‐monophosphate (1). cycloSaligenyl‐pyranose‐1‐monophosphates 6−11 were obtained by a phosphitylation/oxidation procedure starting from appropriately protected D‐pyranoses. The chemical hydrolysis data and the involved hydrolysis mechanisms of cyclosaligenyl‐mannose‐1‐monophosphates 6−9 and their epimeric glucose analogues 10, 11 are reported. Furthermore, the biological activity of cycloSal‐mannose‐1‐phosphates 6−9 was tested in vitro in PMM‐2‐deficient fibroblasts. 3‐Methyl‐cycloSal‐2,3,4,6‐tetra‐O‐acetyl‐α‐D‐mannopyranose‐1‐monophosphate (8) showed a total correction of the phenotype, thus proving the delivery of mannose‐1‐phosphate. This may offer a suitable possibility for a therapy of CDG‐Ia. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Diastereoisomeric Molecular Knots by Combination of Central and Topological Chiralities
Authors: Lukin Oleg , Yoneva Albena , Vögtle Fritz 
Published: March 2004

AbstractWe report an unprecedented example of diastereoisomerism created by reaction of topologically chiral molecular knots (knotanes) bearing hydroxy groups with centrochiral (1S)‐(+)‐camphor‐10‐sulfonyl chloride. The diastereoisomers of knotanes bearing on their periphery one and three camphorsulfonyl units have been completely separated using commercial silica gel (Kromasil) and chiral (Chiralpak AD) HPLC columns respectively. The circular dichroisms of the separated samples have been measured and consequences of the chiral induction discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Is the North Atlantic oscillation a random walk? A comment with further results
Authors: Mills Terence C. 
Published: March 2004

AbstractTime series on the North Atlantic oscillation (NAO) have been subject to considerable analysis in recent years, with the consensus emerging that the data are not characterized by a random walk process. However, no consensus has yet emerged concerning the short run correlation structure of the data. This comment explores the time series properties of the NAO in more detail, using testing and modelling procedures that have found wide application in areas such as economics and finance. A structural time series model provides a comprehensive explanation of the index's rich dynamics, there being a slowly changing level component and a cyclical component having a period of approximately 7.5 years. These are dominated, however, by an irregular component, whose presence makes accurate forecasting of the index problematic. Copyright © 2004 Royal Meteorological Society
Modification of growing‐season surface temperature records in the northern great plains due to land‐use transformation: verification of modelling results and implication for global climate change
Authors: Mahmood Rezaul , Hubbard Kenneth G. , Carlson Christy 
Published: March 2004

AbstractLand‐use and land‐cover change can modify near‐surface atmospheric condition. Mesoscale modelling studies have shown that modification in land use affects near‐surface soil moisture storage and energy balance. Such a study in the Great Plains showed that changes in land use from natural grass to irrigated agriculture enhanced soil water storage in the root zone and increased latent energy flux. This increase in latent energy flux would correspond to a decrease in sensible heat flux and, therefore, modify near‐surface temperature records. To verify this deduction, we have investigated the changes in the historical near‐surface temperature records in Nebraska, USA. We have analysed the long‐term mean monthly maximum, minimum, and monthly mean air temperature data from five irrigated and five non‐irrigated sites. The cooperative weather observation (coop) network is the source of the data. We have found that there is a clear trend in decreasing mean maximum and average temperature data for irrigated sites. For example, York, NE, reports that the mean maximum growing season temperature is decreasing at the rate −0.01°C year−1. The results from non‐irrigated sites indicated an increasing trend for the same parameters. The data from Halsey, NE, indicate a +0.01°C year−1 increase in this century. In addition, we have conducted similar analyses of temperature data for the National Climatic Data Center's Historical Climatic Network data set for the same locations. The results are similar to that obtained with the coop data set. Further investigation of dew‐point temperature records for irrigated and non‐irrigated sites also show an increasing and decreasing trend respectively. Therefore, we conclude that the land‐use change in the Great Plains has modified near‐surface temperature records. Copyright © 2004 Royal Meteorological Society
A 3 year climatology of rainfall characteristics over tropical and subtropical South America based on tropical rainfall measuring mission precipitation radar data
Authors: de Angelis Carlos F. , Mcgregor Glenn R. , Kidd Chris 
Published: March 2004

AbstractTropical Rainfall Measuring Mission precipitation radar data acquired during the period 1 January 1998 to 31 December 2000 over tropical and subtropical South America were used to evaluate the ability of the PR2A25 algorithm in estimating and modelling some rainfall characteristics near the surface. Harmonic analysis applied to the 3 h mean rain rate images successfully modelled the rainfall dynamics over the study area and revealed the extent and propagation of rain bands from the western and eastern Amazon towards its interior, and from western subtropical South America towards the east. It is suggested that rain bands that originate along the eastern slopes of the Andes Cordillera during the first hours of the day and then propagate towards the Amazon interior are possibly due to the convergence of cold katabatic flows from the Andes with warm and moist air present in the foothills of the mountains. This contrasts with previous studies that propose the propagation of precipitation systems from the eastern Amazon towards the Andes Mountains. As study results are based on precipitation radar data with a low sampling rate this bears significant implications for the conclusions drawn. Therefore, study results should be considered as exploratory more than as definitive. Copyright © 2004 Royal Meteorological Society
Assessing two different climatic models and the NCEP–NCAR reanalysis data for the description of winter precipitation in the Iberian Peninsula
Authors: Nieto Susana , Dolores Frías M. , Rodríguez‐Puebla Concepción 
Published: March 2004

AbstractThe main questions motivating this study are: Can climate simulations describe the observations? To what extent can we use climate models to predict climate change? For this purpose, an analysis was made of the correspondences and/or discrepancies between observed winter precipitation data and the data from the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis project, and from two global climatic models: ECHAM4/OPYC3 and HadCM3. The data used correspond to the accumulated winter precipitation for the period 1949–2000, and comparisons of the mean and variability patterns were made. The methods used were principal components analysis, to break down variability and reduce the dimensions of the fields, and correlation and cross‐spectrum analyses for comparison of the time series. For all these, we studied the suitability of their average distributions, as well as their modes of spatial and spectral variability. The results for the Iberian Peninsula show good agreement between the precipitation data of the NCEP–NCAR reanalysis and the observations, both in the average analysis and in the main modes of spatial and time variability. Therefore, the reanalysis data were proved to be a good resource for interpreting climate variations. As regards the climatic models considered, in general the results point to their suitability for describing the spatial distribution of winter precipitation, whereas the spectral association is less appropriate. The variability of the precipitation data was related to circulation patterns and teleconnection indices, such as the North Atlantic oscillation and the Arctic oscillation. The results allow us to conclude that the discrepancies between the two models and observations must be due to a weak representation of the interannual variability. Copyright © 2004 Royal Meteorological Society
Guided‐wave characteristics of periodic microstrip lines with inductive loading: Slow‐wave and bandstop behaviors
Authors: Zhu Lei 
Published: March 2004

AbstractGuided‐wave characteristics of planar periodic microstrip lines with inductive loading are investigated by resorting to the unit‐length transmission parameters of an equivalent transmission line. By applying the SOC de‐embedding technique, the above two quantities are effectively extracted from the full‐wave MoM modeling of a microstrip line with finite periodic cells. Extensive results at first confirm the slow‐wave behavior such that both real parts of such two quantities rise up slowly and then rapidly with frequency. Further, they demonstrate, for the first time, the guided‐wave bandstop characteristic with non‐zero attenuation constant and imaginary characteristic impedance. Five‐cell periodic microstrip circuits are then designed and fabricated for theoretical and experimental verification. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 77–79, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20052
A new class of improved‐efficiency THz filters for on‐chip detection of biomaterials
Authors: Stewing F. , Kleine‐Ostmann T. , Koch M. 
Published: March 2004

AbstractIn a recent breakthrough experiment, the marker‐free on‐chip analysis of DNA using THz voltage pulses propagating along a resonant thin‐film microstrip line was demonstrated. However, the large area of standard filters used in this experiment requires amounts of DNA material that exceed the amount used in state‐of‐the‐art biochip readers. Based on numerical simulations, in this paper we present a new class of filters with increased sensitivity, which require much less DNA material, and propose a new improved measurement scheme. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 79–82, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20053
Variable‐gain amplifier for adaptive antenna control at the 2.4‐GHz ISM‐band
Authors: Multanen Miikka , Salonen Pekka , Kivikoski Markku 
Published: March 2004

AbstractA variable‐gain amplifier for an adaptive antenna at the ISM band is presented. The amplifier consists of three stages and has a digital control. The device is made on a printed circuit board. The amplifier's maximum gain, noise figure, and output compression point are 31.2 dB, 5 dB, and 8.6 dBm, respectively. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 82–85, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20054
A compact and low‐loss 1 × 2 wavelength MUX/DEMUX based on a multimode‐interference coupler using quasi state
Authors: Sam Y. L. , Won Y. H. 
Published: March 2004

AbstractIn this paper, we propose a compact multimode‐interference‐based wavelength MUX/DEMUX. By using the quasi‐output state, the device length can be greatly reduced. The device performances are numerically investigated by using the finite‐difference beam‐propagation method (FD‐BPM). Simulation results show that the device performances, in terms of coupling loss and extinction ratio, are enhanced. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 86–88, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20055
A novel superstrate gain‐enhanced antenna with lateral metallic walls
Authors: Bernard L. , Loison R. , Gillard R. , Lucidarme T. 
Published: March 2004

AbstractBased on gain‐enhancement methods, a narrow single‐superstrate antenna with metallic walls is proposed. The associated resonance conditions are established and a high‐gain antenna with a wide H‐plane beamwidth is designed at 2 GHz. Both simulated and measured results are presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 93–96, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20058
A novel dual‐band printed‐dipole antenna using CRC structure
Authors: Liu Y. F. , Xue Q. , Chan C. H. 
Published: March 2004

AbstractThis paper presents a new approach to the realization of dual‐band operation in a single printed‐dipole antenna by incorporating compact resonant cell (CRC) structures. A dual‐band antenna that operates at 900 MHz and 2.4 GHz is constructed to illustrate the design methodology. The overall length of the proposed antenna is reduced by 12%, in comparison with that of the conventional design. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 105–106, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20061
Modeling of light propagation through step‐like discontinuities in slab dielectric waveguides
Authors: Romanova E. A. , Gaal S. B. 
Published: March 2004

AbstractOne‐way light propagation through a steplike discontinuity of dielectric‐slab waveguide is simulated by using the finite‐difference beam‐propagation method (FD‐BPM) and the Green's function method. The validity of the slowly varying envelope approximation in modeling of the total field distribution and the radiation‐field distribution is analyzed. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 108–114, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20063
A simple theoretical model for rectangular microstrip resonator with stubs
Authors: da Costa Karlo Q. , Dmitriev Victor 
Published: March 2004

AbstractIn this work, we present a simple theoretical analysis of a compact rectangular microstrip resonator with stubs. The analytical model is based on a recursive algorithm for a transmission line loaded with capacitive stubs. We calculate the input impedance and the resonant frequency of this resonator and analyse the dependence of these parameters on the number and dimensions of the stubs. The numerical results are compared with those obtained by other methods and with experimental data. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 119–123, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20066
Reduced conditions for the constitutive parameters of lossy bi‐anisotropic media
Authors: Tan Eng Leong 
Published: March 2004

AbstractThis paper presents reduced conditions for the constitutive parameters of lossy bi‐anisotropic media. It is shown that only two separate dyadic conditions, in contrast to the previously reported four, will be necessary and sufficient to characterize a medium as lossy. For the gyrotropic bi‐anisotropic case revisited, it is found that these media call for merely two scalar conditions for their constitutive parameters, in contrast to the nine (reducible to seven) conditions formulated previously. The reduced dyadic and scalar conditions will simplify analysis of the physical realizability and the valid range of parameter values for new composite media. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 133–135, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20070
Angle of arrival measurement using an ultra fast transient analyzer and music algorithm
Authors: Benlarbi‐Delaï Aziz , Rolland Nathalie , Ghis Anne , Rolland Paul‐Alain 
Published: March 2004

AbstractThis paper describes a cross‐fertilization approach between a novel sub‐nanosecond transient analyzer based on nonsimultaneous spatial sampling and a high‐resolution algorithm based on subspace decomposition and the eigen‐analysis method. Our targeted goal is the real‐time measurement of the angle of arrival (AOA) devoted to a connected vehicle in the field of intelligent transport systems (ITS). © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 141–144, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20073