bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Delocalization in Linearly π‐Conjugated Systems: A Concept for Quantitative Analysis
Authors: Giuffreda Maria Grazia , Bruschi Maurizio , Lüthi Hans Peter
Published: October 2004

Donor‐ and/or acceptor‐substituted π‐conjugated systems represent an important class of compounds in organic chemistry. However, up to now, a general method to quantitatively address the efficiency of a conjugated path is still missing. In this work, a novel computational approach based on deletion energies and on second‐order orbital interaction energies in a natural bond orbital (NBO) scheme is employed to quantitatively assess (“measure”) delocalization energies. Moreover, the purpose of this work is to assess the efficiency of distinct π‐conjugated paths, that is, geminal, cis, and trans, as well as to predict the impact of substituents on a given backbone. This study is focused on various mono‐, di‐, tri‐, and tetrasubstituted tetraethynylethenes (TEEs). These model systems are suitable for our analysis, because they offer distinct conjugation paths within the same molecule, and can also be substituted in multiple ways. Differences between conjugation paths, the effect of neighbor paths, and the impact of donor and acceptor substituents on the various paths are discussed.
CC Double‐ and Triple‐Bond Formation from Reactions of B Atoms with CO: Experimental and Theoretical Characterization of OBBCCO and OBCCBO Molecules in Solid Argon
Authors: Zhou Mingfei , Jiang Ling , Xu Qiang
Published: October 2004

Reactions of boron atoms with CO molecules in solid argon form the following boron carbonyl species (which have been reported earlier): BCO, BBCO, OCBBCO, B(CO)2, and B4(CO)2. The OCBBCO molecule underwent a photochemical rearrangement where CO was activated to form the OBBCCO and OBCCBO molecules. The new molecules were identified on the basis of isotopic IR studies with 10B, 11B, 13C16O, 12C18O, and carbon dioxide mixtures in addition to comparison with quantum‐chemical calculations of isotopic frequencies. Theoretical analyses showed that the OBBCCO and OBCCBO molecules are linear with CC double and triple bonding, respectively, and lie at a much lower energy than the linear OCBBCO structure.
Two‐Component Dendritic Gel: Effect of Stereochemistry on the Supramolecular Chiral Assembly
Authors: Hirst Andrew R. , Smith David K. , Feiters Martin C. , Geurts Huub P. M.
Published: October 2004

The self‐assembly of diaminododecane solubilised by four different stereoisomeric dendritic peptides to form gel‐phase materials in toluene was investigated. The second generation dendritic peptides were based on D‐ and L‐lysine building blocks, and each contained three chiral centres. By designing dendritic peptides in which the configurations of the chiral centres were modified, and applying them as gelator units, the assembly of stereoisomers could be investigated. In all cases, the self‐assembly of gelator units resulted in macroscopic gelation. However, the degree of structuring was modulated by the stereoisomers employed, an effect which changed the morphology and macroscopic behavior of the self‐assembled state. Enantiomeric (L,L,L or D,D,D) gelator units formed fibrous molecular assemblies, whilst the racemic gel (50 % L,L,L : 50 % D,D,D) formed a flat structure with a “woven” appearance. Gelator units based on L,D,D or D,L,L dendritic peptides also formed fibrous assemblies, but small‐angle X‐ray scattering indicated significant morphological differences were caused by the switch in chirality. Furthermore, the macroscopic stability of the gel was diminished when these peptides were compared with their L,L,L or D,D,D analogues. In this paper it is clearly shown that individual stereocentres, on the molecular level, are directly related to the helicity within the fibre. It is argued that the chirality controls the pattern of hydrogen bonding within the assembly, and hence determines the extent of fibre formation and the macroscopic gel strength.
Injecting Electronic Excitation Energy into an Artificial Antenna System through an Ru2+ Complex
Authors: Bossart Olivia , De Cola Luisa , Welter Steve , Calzaferri Gion
Published: October 2004

The Ru2+ complex [Ru(bpy)2(bpy‐ph4‐Si(CH3)3)]2+ can be electrostatically bound to the negatively charged channel entrances of dye‐loaded zeolite L crystals where it acts as a functional stopcock molecule. Impressive electronic triplet–singlet excitation energy transfer from the Ru2+ complex to the acceptor dye oxazine 1 (Ox1) located inside the channels can be observed when the donor molecule is selectively excited. Time‐resolved luminescence experiments have been performed on the separate components and on the assembled donor–acceptor material. The luminescence lifetime of the Ru2+ complex attached to the zeolite is reduced by a factor of 30 when Ox1 acceptor molecules are present. The fluorescence decay of Ox1 incorporated in zeolite L is single exponential with a lifetime of 3 ns. The much longer lifetime in zeolite L than in solution is due to the fact, that the diethyl groups are sterically restricted when the dye is inside the host.
Quasi‐wavelet solution of diffusion problems
Authors: Jiashi Tang , Zhuyong Liu
Published: October 2004

A new method, quasi‐wavelet method, is introduced for solving partial differential equations of diffusion which are important to chemical and mechanical engineering. A new scheme for the extension of boundary conditions is proposed. The quasi‐wavelet method is utilized to discretize the spatial derivatives, while the Runge–Kutta scheme is employed for the time advancing. The problems of particle diffusion in the electrochemistry reaction and temperature diffusion in plates are studied. Quasi‐wavelet solution of the former problem is compared with those of a finite difference method. Solution of the latter problem is calibrated by analytical solution. Numerical results indicate that the quasi‐wavelet approach is very robust and efficient for diffusion problems. Copyright © 2004 John Wiley & Sons, Ltd.
Formulations and analysis of the spectral volume method for the diffusion equation
Authors: Sun Yuzhi , Wang Z.J.
Published: October 2004

The spectral volume (SV) method is a newly developed high‐order finite volume method for hyperbolic conservation laws on unstructured grids. It has been successfully demonstrated for multi‐dimensional Euler equations. We wish to extend the SV method to the Navier–Stokes equations. As a first‐step towards achieving that goal, the SV method is extended to and tested for the diffusion equation. In this paper, we present three different formulations of the spectral volume method for the diffusion equation. The first formulation yields an inconsistent and unstable scheme, while the other two formulations are consistent, convergent and stable. A Fourier type analysis is performed for all the formulations, and the analysis agrees well with numerical results. Copyright © 2004 John Wiley & Sons, Ltd.
Curve linearization and discretization for meshing composite parametric surfaces
Authors: Laug P. , Borouchaki H.
Published: October 2004

In the context of composite parametric surface meshing using a direct or an indirect (via the meshing of parametric domains) method, the discretization of interface curves joining patches plays a central part. In the case of an indirect method, the discretization of interface curves must be taken back to parametric spaces. This is usually done using root finding techniques for generally non‐linear parametric functions. This paper presents a new linearization technique to determine the above correspondence. In addition, this linearization of interface curves makes it possible to obtain their discretization without explicitly computing the arc length. This method has been implemented in a surface mesh generator and an example from Fluid Mechanics is given to illustrate the pertinence of the proposed approach. Copyright © 2004 John Wiley & Sons, Ltd.
Reduction in radiated emission from multilayer PCBs by the layer structure shielding a power plane
Authors: Haga Satoru , Nakano Ken , Hashimoto Osamu
Published: October 2004

Strong radiated emission is caused by the power and ground plane resonance in multilayer printed circuit boards. The emission cannot be completely reduced as far as parallel plate structure with open edges. Therefore, a novel printed board has been proposed, which has symmetrical ground‐power‐ground layer stack‐up with the peripheral edges of the two ground planes connected to shield the power plane. It has been experimentally verified that the emission can be reduced to a degree that no peak can be observed and that the power input to the signal trace is hardly transformed to the radiated power. Further, since no electronic components or interconnect area for reduction in the emission are needed in the printed board, the printed board provides extremely useful realization of future higher packaging density. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(2): 50–60, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10193
All digital dividing ratio changeable type phase‐locked loop with a wide lock‐in range
Authors: Yahara Mitsutoshi , Sasaki Hirotoshi , Fujimoto Kuniaki , Sasaki Hirofumi
Published: October 2004

Today the All Digital Phase‐Locked Loop (ADPLL) is applied in many fields. However, previously proposed ADPLLs did not simultaneously implement a wide lock‐in range and a fast pull‐in. The proposed Dividing ratio Changeable ADPLL (DCPLL) is a method for automatically changing the dividing ratio of the counter in response to the frequency of the input signal and can obtain an extremely wide lock‐in range. The output jitter will always be three or fewer pulses of the fast reference clock. By performing remainder control of the dividing ratio during multiplication, an output signal that is a multiple of the constant pulse interval and has jitter characteristics equivalent to the basic operation can be obtained. Furthermore, the initial pull‐in is finished in one period of the input signal, which is the shortest time. Consequently, since a wide lock‐in range and a fast pull‐in can be simultaneously achieved, this DCPLL has many general‐purpose applications and is effective in the reference clock source in all types of portable devices and in bit synchronization in data communication. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(2): 41–49, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20138
Suppression method of grating lobe by pulse power transmission from an array antenna
Authors: Takechi Osamu , Matsumoto Hiroshi , Shinohara Naoki , Hashimoto Kozo
Published: October 2004

A new method is proposed for suppressing the grating lobe (GL) by pulse power transmission from an array antenna. GL suppression relies on the fact that the maximum electric field value is not synthesized by the waves from the array antenna at the undesired points even if the maximum electric field is attained at the desired receiving point, because the pulses emerging from different antenna elements do not overlap. Two computer simulations are carried out to confirm this suppression effect. In the simulation using a two‐element array antenna with an element spacing exceeding one wavelength, the GL suppression effect is confirmed with a pulsed wave even though the GL is generated with a continuous wave. In pulsed power transmission simulation with many elements, the GL suppression effect is enhanced with an increasing number of elements. It is also found that the effect increases as the pulse width becomes smaller. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(2): 1–10, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20156
Characteristics of Sr+ ions in an RF trap
Authors: Hirano Iku , Yoda Jun
Published: October 2004

We have developed a system for generating light by doubling the frequency (second‐harmonic generation) of a high‐power semiconductor laser, with high frequency stability provided by locking to the absorption line of a hollow‐cathode lamp. Once this system was built, we constructed an ion trap and used light from the system to measure the characteristics of the trapped ions. By illuminating the ions with both a pump laser and a repumping laser, we were able to measure the characteristics of the ion fluorescence. We used rate equations to analyze our measurements. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(11): 1–9, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20088
Control strategies in human pinch motion to perceive the hardness of an elastic object
Authors: Fujita Kinya
Published: October 2004

This paper considers human pinch motion to perceive the hardness of an elastic object. The pinch force, the displacement of the object, and the contact area are measured, and the control rule for the pinch motion is examined experimentally. Pair comparison tasks for hardness are tried for 10 subjects, using five different elastic objects of different hardness. It is found that the displacement changes for 91% of the maximum value, and the force changes for 84% of the maximum value, depending on the difference of the elastic constant. But the change of the contact area is 26%, and is less related to the elasticity. Calculating the imaginary displacement based on the equilibrium point control hypothesis, the change due to the hardness is 29%. Consequently, it is suggested that in pinch motion to perceive hardness, the imaginary displacement is maintained constant and the contact area is maintained almost constant. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(11): 28–37, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20126
A sound synthesis system “Otkinshi” on Windows
Authors: Osaka Naotoshi , Sakakibara Ken‐ichi , Hikichi Takafumi
Published: October 2004

In this paper the authors describe “Otkinshi,” a new sound synthesis system with functions for sound synthesis, modification, and performance in a visual environment under Windows. Prior sound synthesis systems for music using a visual control environment have been centered on object boxes for procedures such as a unit generator or pitch. However, the authors' system takes into consideration ease‐of‐use for synthesis and modification when moving among different levels such as arranging several completed sounds in space and time, represents the sound objects that are data as a visual unit such as icons, and allows for synthesis and modification using the above and icons representing operation objects. A sound object includes an operation history, and so actions created through trial and error can be used again through visual programming. On this foundation, sound modification based on a sinusoidal model represents the characteristic feature of the system, and includes morphing and vibrato control. Synthesis and morphing functions using a physical model are also built‐in. The authors have shown that the system successfully completed two real performances of computer music, and is effective as a general tool for creating music. At present, the authors have asked composers and students at musical colleges to use the system, and are starting to exchange opinions. The authors expect their system to become a valuable tool for the creation of multimedia content, as well as for computer music. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(11): 63–72, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20129
(Schiff‐base)CuII Complexes with Phenolate‐Oxygen/Chloro or ‐Oxygen/Azido Mixed Bridges − Syntheses, Crystal Structures and Magnetic Properties
Authors: Jiang Yun‐Bo , Kou Hui‐Zhong , Wang Ru‐Ji , Cui Ai‐Li
Published: October 2004

Four new CuII complexes of formulae [Cu3(SE)2(H2O)2Cl3]Cl·6H2O (1), Cu3(SE)2(N3)4(DMF)2 (2), Cu(SE)N3·DMF (3) and Cu(SE)N3·Cu(SE)N3 (4) with tridentate Schiff‐base ligands SE−, derived from condensation of N,N‐dimethylethylenediamine with salicylaldehyde, have been synthesised and characterised by IR spectroscopy, X‐ray structural analyses and variable‐temperature magnetic susceptibility measurements. Complex 1 has an alternating phenoxy‐ and chloro‐bridged 1D chain structure. Complex 2 possesses trinuclear units in which the CuII ions are bridged by single end‐on (µ‐1,1) azido ligands. Uniformly spaced 1D chains with end‐to‐end (µ‐1,3) azido bridges are found in 3 and 4. As expected, complexes 1 and 2 exhibit antiferromagnetic and ferromagnetic exchange, respectively. Compounds 3 and 4 show unusual ferromagnetic coupling though the 1,3‐azido pathways. Theoretical simulations have been carried out in order to evaluate the magnitude of the magnetic exchange and the magneto‐structural correlation has been investigated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Comparison of Analogous 4f‐ and 5f‐Element Compounds: Syntheses, X‐ray Crystal Structures and Catalytic Activity of the Homoleptic Amidinate Complexes [M{MeC(NCy)2}3] (M = La, Nd or U)
Authors: Villiers Claude , Thuéry Pierre , Ephritikhine Michel
Published: October 2004

Reaction of UCl4 with [Li{RC(NCy)2}(THF)]2 (R = Me, 1a; R = nBu, 1b) in THF gave the tris(amidinate) compounds [U{RC(NCy)2}3Cl] (R = Me, 2a; R = nBu, 2b) which were reduced with lithium powder in THF to the homoleptic complexes [U{RC(NCy)2}3] (R = Me, 3a; R = nBu, 3b). Complexes 1a, 1b, 2a and 3a have been crystallographically characterized. Comparison of the crystal structure of 3a with those of the lanthanide analogues [Ln{MeC(NCy)2}3] (Ln = La, 4; Ln = Nd, 5; Ln = Yb, 6) shows that the average U−N distance is shorter than expected from a purely ionic bonding model. The uranium complex 3a is much less efficient than its lanthanide counterparts in the catalytic polymerization of ϵ‐caprolactone because of its rapid oxidation into UIV species. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
C2‐Symmetric Fluorous Diamines and Diimines as Ligands for Metal‐Catalysed Asymmetric Cyclopropanation of Styrene
Authors: Shepperson Ian , Quici Silvio , Pozzi Gianluca , Nicoletti Marcello , O’Hagan David
Published: October 2004

Perfluoroalkyl‐substituted, enantiopure C2‐symmetric N and N,O ligands showing affinity either for standard organic solvents or perfluorocarbons have been conveniently prepared from readily available precursors. Preformed cobalt(II) and in‐situ‐generated copper(I) complexes of these ligands were tested as catalysts in the metal‐catalysed cyclopropanation of styrene with diazoacetates. Under optimised reaction conditions, which include the use of a fluorous biphasic system and short reaction times, the copper complex of a C2‐symmetric diamine afforded promising results (yield = 77%, trans/cis = 67:33, ee of the trans isomer = 62%) and could be easily separated from the products by simply decanting the fluorous phase. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
2,2‐Bis(3‐Amino‐4‐hydroxyphenyl)hexafluoropropane Modified Glassy Carbon Electrodes as Selective and Sensitive Voltammetric Sensors. Selective Detection of Dopamine and Uric Acid
Authors: Milczarek Grzegorz , Ciszewski Aleksander
Published: October 2004

2,2‐bis(3‐Amino‐4‐hydroxyphenyl)hexafluoropropane (BAHHFP) was electro‐polymerized oxidatively on glassy carbon by cyclic voltammetry. The activity of the modified electrode towards ascorbic acid (AA), uric acid (UA) and dopamine (DA) was characterized with cyclic voltammetry and differential puls voltammetry (DPV). The findings showed that the electrode modification drastically suppresses the response of AA and shifts it towards more negative potentials. Simultaneously an enhancement of reaction reversibility is seen for DA and UA. Unusual, selective preconcentration features are observed for DA when the polymer‐modified electrode is polarized at negative potential. In a ternary mixture containing the three analytes studied, three baseline resolved peaks are observed in DPV mode. At physiological pH 7.4, after 5 min preconcentration at −300 mV, peaks positions were −0.073, 0.131 and 0.280 V (vs. Ag/AgCl) for AA, DA and UA, respectively. Relative selectivities DA/AA and UA/AA were over 4000 : 1 and 700 : 1, respectively. DA response was linear in the range 0.05–3 μM with sensitivity of 138 μA μM−1 cm−2 and detection limit (3σ) of 5 nM. Sensitive quantification of UA was possible in acidic solution (pH 1.8). Under such conditions a very sharp peak appeared at 630 mV (DPV). The response was linear in the range 0.5–100 μM with sensitivity of 4.67 μA μM−1 cm−2 and detection limit (3σ) of 0.1 μM. Practical utility was illustrated by selective determination of UA in human urine.
Trace Analysis of Al (III) Ions Based on the Redox Current of a Conducting Polymer
Authors: Seol Hyunju , Shin Sung Chul , Shim Yoon‐Bo
Published: October 2004

A conducting polymer was electrochemically prepared on a Pt electrode with newly synthesized 3′‐(4‐formyl‐3‐hydroxy‐1‐phenyl)‐5,2′ : 5′,2″‐terthiophene (FHPT) in a 0.1 M TBAP/CH2Cl2 solution. The polymer‐modified electrode exhibited a response to proton and metal ions, especially Al(III) ions. The poly[FHPT] was characterized with cyclic voltammetry, EQCM, and applied to the analysis of trace levels of Al(III) ions. Experimental parameters affecting the response of the poly[FHPT] were investigated and optimized. Other metal ions in low concentration did not interfere with the analysis of Al(III) ions in a buffer solution at pH 7.4. The response was linear over the concentration range of 5.0×10−8–7.0×10−10 M, and the detection limit was 5.0×10−10 M using the linear sweep voltammetry (LSV). Employing the differential pulse voltammetry (DPV), the response was linear over the 1.0×10−9–5.0×10−11 M range and the detection limit was 3.0×10−11 M. The relative standard deviation at 5.0×10−11 M was 7.2% (n=5) in DPV. This analytical method was successfully verified for the analysis of trace amounts of Al(III) ions in a human urine sample.
Separation of positional isomers by cucurbit[7]uril‐mediated capillary electrophoresis
Authors: Xu Li , Liu Si‐Min , Wu Cheng‐Tai , Feng Yu‐Qi
Published: October 2004

A novel macrocyclic molecule, cucurbit[7]uril (CB[7]) was for the first time employed as an additive in capillary electrophoresis (CE). In similarity to other macrocyclic molecules, such as crown ethers, cyclodextrins (CDs) and calixarenes, CB[7] can form inclusion complexes with a variety of guest molecules due to its inner cavity. Thus, it can be used like other macrocyclic molecules to manipulate selectivities in CE. During the running process, CB[7] bears a positive charge under the studied pH range (pH 2.5–7) and can be adsorbed onto the inner wall of a fused‐silica capillary, leading to a reversal of the electroosmotic flow (EOF). Electrophoretic behaviors of nitrotoluene, nitrophenol, nitroaniline, and methylaniline isomers were studied under various conditions. The electrophoretic separations of the isomers can be accomplished with a buffer containing CB[7]. Furthermore, a probable separation mechanism in the presence of CB[7] was also proposed.
Development and in situ synthesis of monolithic stationary phases for electrochromatographic separations
Authors: Delaunay‐Bertoncini Nathalie , Demesmay Claire , Rocca Jean‐Louis
Published: October 2004

Organic monolithic stationary phases have been synthesized in UV‐transparent fused‐silica capillaries, which have been used as test format of microfabricated device channels. The columns have been prepared by in situ polymerization of butyl acrylate, lauryl acrylate, 1,3‐butanediol diacrylate, and 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) in a ternary porogenic solvent. The resulting stationary phases have been tested in capillary electrochromatography and exhibited reversed‐phase chromatography behavior toward neutral solutes. Van Deemter plots of phenylureas and polycyclic aromatic hydrocarbons, selected as model analytes, have been determined to study the influence of various polymerization and separation parameters on properties of the monoliths. The amount of AMPS and the nature of monomers in the polymerization solution have been thus adjusted. It has been observed that the ionic strength of the mobile phase may affect significantly the efficiency of the separation. The effect of the percentage of acetonitrile in the mobile phase on efficiency and permeability of the organic monoliths has also been investigated. Efficiencies greater than 300 000 plates/m have been obtained with the test compounds. Stability and reproducibility have been extensively studied.
Design and performance of a light‐emitting diode detector compatible with a commercial capillary electrophoresis instrument
Authors: Johns Cameron , Macka Miroslav , Haddad Paul R.
Published: October 2004

Indirect photometric detection in capillary electrophoresis (CE) has been predominantly performed in the UV region, in part due to a lack of suitable high‐intensity and low‐noise light sources in the visible spectral region. A new photometric detector based on light‐emitting diodes (LEDs) as light sources and compatible with a commercially available CE instrument has been designed and constructed and its performance evaluated. The utility of this detector was successfully demonstrated by the indirect photometric detection of anions using a dye as probe and absorbance measured in the visible region. The detector exhibited very low baseline noise (around 0.03 mAU), stable output, and improved upper limit of detection linearity (502 mAU) compared with previously used LED detectors. The detector was tested for indirect detection of anions separated with an electrolyte containing 4 mM Orange G as the indirect detection probe, 10 mM histidine as an isoelectric buffer, and 0.05% hydroxypropylmethylcellulose to suppress the electroosmotic flow. Extremely low detection limits were obtained ranging from 0.16–0.36 μM (excluding chloride 0.56 μM), with separation efficiencies in the range of 154 000–274 000 theoretical plates.
Capillary sieving electrophoresis‐micellar electrokinetic chromatography fully automated two‐dimensional capillary electrophoresis analysis of Deinococcus radiodurans protein homogenate
Authors: Michels David A. , Hu Shen , Dambrowitz K. Amy , Eggertson Michael J. , Lauterbach Kevin , Dovichi Norman J.
Published: October 2004

We report the one‐ and two‐dimensional (1‐D and 2‐D) capillary electrophoresis separation of Deinococcus radiodurans protein homogenate. Proteins are labeled with the fluorogenic reagent 3‐(2‐furoyl)quinoline‐2‐carboxaldehyde (FQ), which reacts with lysine residues and creates a highly fluorescent product. Detection is by laser‐induced fluorescence. 1‐D capillary sieving electrophoresis (CSE) produces over 150 000 plates and micellar electrokinetic capillary chromatography (MEKC) produces over 900 000 plates for components in a D. radiodurans protein homogenate. In a 2‐D separation, proteins are first separated by CSE. Fractions are repetitively transferred to a second capillary for further separation based on MEKC. The 2‐D separation has a ∼550 spot capacity. Over 150 components are partially resolved from the homogenate. Resolution is limited in the first dimension by diffusion of proteins during the long separation period and in the second dimension by the combination of a long fraction‐transfer time and short separation period.
Noncovalent labeling of myoglobin for capillary electrophoresis with laser‐induced fluorescence detection by reconstitution with a fluorescent porphyrin
Authors: de Jong Ebbing P. , Melanson Jeremy E. , Lucy Charles A.
Published: October 2004

Traditional protein labeling reactions for capillary electrophoresis (CE) with laser‐induced fluorescence (LIF) detection suffer from a variety of disadvantages. The reactions can be nonquantitative on a reasonable time scale, require relatively high concentrations of protein and fluorophore, and can give multiple reaction products that can not be separated. Herein, we describe a new noncovalent labeling technique that is rapid, selective for myoglobin, and gives a simple reaction product. Myoglobin is denatured with either 5.4 M urea or low pH (2.0). The denatured myoglobin releases its nonfluorescent heme group. A fluorescent porphyrin (protoporphyrin IX (PPIX) or its zinc (II) complex, Zn‐PPIX), is added to the mixture and the solution conditions are altered (dilute to 0.54 M urea or adjust pH to 7.0) to allow myoglobin refolding. Upon refolding, the protein incorporates PPIX from solution, thus making the reaction product fluorescent. The experimental conditions have been optimized for both urea and low‐pH denaturation of myoglobin. The latter procedure produces a detection limit of 50 nM. Alternatively, the reaction can be performed without denaturation by a simple exchange of the porphyrins. The use of Zn‐PPIX yields the most efficient reaction. The low‐pH reaction is unaffected by a 2000‐fold excess of bovine serum albumin.
Separation of enantiomers in microemulsion electrokinetic chromatography using chiral alcohols as cosurfactants
Authors: Zheng Zhi‐Xia , Lin Jin‐Ming , Chan Wing‐Hong , Lee Albert W. M. , Huie Carmen W.
Published: October 2004

A novel chiral microemulsion, which involved the use of chiral alcohols as cosurfactants, was demonstrated for the enantiomeric separation of a number of pharmaceutical drugs in microemulsion electrokinetic chromatography (MEEKC). The chiral alcohols investigated were optically active 2‐alkanols, with the alkyl chain length having carbon number ranging from 4 to 7. The data indicated that, except for R‐(—)‐2‐butanol, the use of R‐(—)‐2‐pentanol, R‐(—)‐2‐hexanol or R‐(—)‐2‐heptanol as the chiral cosurfactant resulted in the baseline or partial resolution of most of the test solutes, i.e., (±)‐norephedrine, (±)‐ephedrine, DL‐nadolol, and DL‐propranolol. In addition to the chain length of the chiral 2‐alkanols, the effects of other experimental conditions, such as the concentration and chirality of the 2‐alkanols, as well as the pH of the run buffer and the oil phase of the microemulsion, on the enantiomeric separation of the test solutes were also investigated. An interesting finding was that the water‐immiscible organic solvent (oil core) within the microemulsion droplets appeared to play an important role in the chiral separation mechanism. Also, the importance of hydrogen bonding between the test solutes ((±)‐ephedrine and related compounds) and the chiral microemulsion was demonstrated, as it was not possible to resolve a pair of enantiomers which lacked a β‐amino proton (i.e., (±)‐N‐methyl ephedrine) under optimized run buffer conditions (e.g., 5.0% R‐(—)‐2‐hexanol, 0.8% n‐octane, and 3.5% SDS in 90.7% borate buffer at pH 9.2).
Total serum protein N‐glycome profiling on a capillary electrophoresis‐microfluidics platform
Authors: Callewaert Nico , Contreras Roland , Mitnik‐Gankin Luba , Carey Loucinda , Matsudaira Paul , Ehrlich Daniel
Published: October 2004

We implemented 8‐aminopyrene‐1,3,6‐trisulfonic acid (APTS)‐labeled asparagine‐linked glycan (N‐glycan) profiling on a microfluidic electrophoresis platform. Using 11.5 cm effective length etched channels and 4% linear polyacrylamide as the separation matrix, the major N‐glycans in human serum were profiled in 12 min with a resolution comparable to what is achieved for these analytes on gel‐based DNA sequencers. This demonstration suggests a practical clinical application for high‐speed compact analyzers which might be uniquely based on microfluidic devices.
Changes in mobile phase ion distribution when combining pressurized flow and electric field
Authors: Eriksson Björn O. , Dahl Magnus , Andersson Magnus B. O. , Blomberg Lars G.
Published: October 2004

The distribution of ions in a capillary with both pressurized flow and an electric field has been studied. We have earlier reported that the overall concentration of ions increase in a capillary with high electric field and a pressurized flow. Now we describe how the ions are distributed in the capillary both along the capillary length and in the radial direction as a result of the parabolic flow profile. We have combined current measurements with finite element techniques in order to get better understanding of the system. We have found that the concentration of the ions that because of the electric mobility moves towards the flow primarily increases at the beginning of the electric field and close to the capillary wall. In view of the results we have proposed an alterative explanation of earlier published results concerning voltage‐induced variation in capacity factors.
Critical aspects of analysis of Micrococcus luteus, Neisseria cinerea, and Pseudomonas fluorescens by means of capillary electrophoresis
Authors: Hoerr Verena , Stich August , Holzgrabe Ulrike
Published: October 2004

Within the frame of our study we investigated Microccocus luteus, Neisseria cinerea, and Pseudomonas fluorescens by means of capillary zone electrophoresis (CZE). They form chains and clusters on a different scale, which can be reflected in the electropherograms. A low buffer concentration of Tris‐borate and Na2 EDTA containing a polymeric matrix of 0.0125% poly(ethylene) oxide (PEO) was used. Key factors were the standardization and optimization of CE conditions, buffer solution, and pretreatment of bacterial samples, which are not transferable to different bacterial strains, in general. The different compositions of the cell wall of on the one hand Gram‐positive (M. luteus) and Gram‐negative (N. cinerea) cocci and on the other hand Gram‐negative, rod‐shaped bacteria (P. fluorescens), are probably responsible for the different pretreatment conditions.
Separation of isomers of acyl glucuronides using micellar electrokinetic capillary chromatography in dynamically coated capillaries
Authors: Hansen Steen H. , Christiansen Ida
Published: October 2004

The acyl glucuronide metabolites of endogenous as well as of xenobiotic compounds may undergo isomerization in vitro as well as in the human body. The parent acyl glucuronide and the isomerization products may react with endogenous protein to form products which in worst cases may act as antigens and thus create an allergic response. In the present paper new methods based on micellar electrokinetic or microemulsion electrokinetic chromatography for the separation of all isomerization products as well as the hydrolysis product of acyl glucuronides are described. In order to perform the separation at lower pH values in a reasonable time dynamically coated capillaries were used. This enables the electroosmotic flow to be high and constant even at low pH. The methods were developed using S‐naproxen‐β‐1‐O‐acyl glucuronide as the model substance. The assignment of the single peaks in the electropherogram was performed tentatively based on the sequential appearance of the isomerization products with time.
Analysis of insecticidal proteins from Bacillus thuringiensis and recombinant Escherichia coli by capillary electrokinetic chromatography
Authors: Luong John H. T. , Male Keith B. , Mazza Alberto , Masson Luke , Brousseau Roland
Published: October 2004

Bacillus thuringiensis and recombinant Escherichia coli proteinaceous protoxins were subject to proteolysis and analyzed by capillary electrokinetic chromatography. Three resulting toxins (65 kDa) were baseline‐resolved within 22 min using a 10 mM borate, pH 11 separation buffer consisting of 25 mM sodium dodecyl sulfate (SDS) and 30 mM phytic acid. The toxins displayed differential interactions with the SDS and phytic acid phases to effect their separation. The ion‐pairing interaction between the analyte and phytic acid was also useful in preventing adsorption to the capillary walls and thus enhanced separation resolution and efficiency. The use of electrokinetic chromatography allows achievement of the separation in a significantly shorter time than conventional high‐performance liquid chromatography (HPLC) using a diethylaminoethyl (DEAE) weak‐anion exchanger.
Multiple sample amplification and genotyping integrated on a single electronic microarray
Authors: Huang Ying , Shirajian Jack , Schroder Astrid , Yao Zuxu , Summers Tamara , Hodko Dalibor , Sosnowski Ron
Published: October 2004

We report a novel method that allows simultaneous in situ amplification and then genotyping of single nucleotide polymorphism (SNP) for multiple samples on a single electronic microarray. The locus coding for one of the common inherited thrombosis risk factors, Factor V Leiden (FVL), was chosen as a model system for SNP analysis. This method combines strand displacement amplification (SDA) with electrophoretic movement and concentration of DNA on electronic microarrays to provide a single platform for DNA amplification and analysis. The method includes: electronic anchoring of allele‐specific SDA amplifiable primers (APs) and a nonamplifiable primer (NAP) to different electrodes, electronic hybridization of genomic DNA from different samples to those primers, in situ amplification of target DNA, and genotyping of FVL. Compared to previous anchored SDA methods, the addition of a NAP improves detection signals by at least 20‐fold. The sensitivity of this method is dependent on the amplification time. Using this method, nine different genomic DNA samples with known FVL genotypes were amplified and correctly genotyped on a single electronic microarray without any contamination between samples. The present method could streamline development of nucleic acid‐based assays in applications of molecular diagnostic, point‐of‐care testing, and forensic detection, which often require the capability to analyze multiple samples efficiently.
Editorial: Electrophoresis 18‐19/2004
Authors: El Rassi Ziad
Published: October 2004

No abstracts.
Drying of Tribenuron, a Thermosensitive Biochemical
Authors: Chen B.‐K.
Published: October 2004

The extension of microwave use in the biochemical industry was explored by drying tribenuron, a thermosensitive biochemical, in a microwave oven and in a thermal vacuum oven. Tribenuron wet cakes, containing a mixture of solvents, methanol and water, were heated at 40 °C in both ovens. Nitrogen purge was used to prevent the decomposition of tribenuron from prolonged heating. Microwave heating dried tribenuron in twenty minutes while the vacuum oven heating required eighteen hours to dry the wet cakes. In addition, the tribenuron quality was maintained under microwave drying, but deteriorated in the thermal vacuum oven. Therefore, microwave technology is more effective in drying tribenuron than conventional vacuum ovens. The results of this study are important for the use of microwave drying on a large scale in biochemical companies.
Optimization of Operating Temperature for Continuous Immobilized Glucose Isomerase Reactor with Pseudo Linear Kinetics
Authors: Faqir N.M.
Published: October 2004

In this work, the optimal operating temperature for the enzymatic isomerization of glucose to fructose using a continuous immobilized glucose isomerase packed bed reactor is studied. This optimization problem describing the performance of such reactor is based on reversible pseudo linear kinetics and is expressed in terms of a recycle ratio. The thermal deactivation of the enzyme as well as the substrate protection during the reactor operation is considered. The formulation of the problem is expressed in terms of maximization of the productivity of fructose. This constrained nonlinear optimization problem is solved using the disjoint policy of the calculus of variations. Accordingly, this method of solution transforms the nonlinear optimization problem into a system of two coupled nonlinear ordinary differential equations (ODEs) of the initial value type, one equation for the operating temperature profile and the other one for the enzyme activity. The ODE for the operating temperature profile is dependent on the recycle ratio, operating time period, and the reactor residence time as well as the kinetics of the reaction and enzyme deactivation. The optimal initial operating temperature is selected by solving the ODEs system by maximizing the fructose productivity. This results into an unconstrained one‐dimensional optimization problem with simple bounds on the operating temperature. Depending on the limits of the recycle ratio, which represents either a plug flow or a mixed flow reactor, it is found that the optimal temperature of operation is characterized by an increasing temperature profile. For higher residence time and low operating periods the residual enzyme activity in the mixed flow reactor is higher than that for the plug flow reactor, which in turn allows the mixed flow reactor to operate at lower temperature than that of the plug flow reactor. At long operating times and short residence time, the operating temperature profiles are almost the same for both reactors. This could be attributed to the effect of substrate protection on the enzyme stability, which is almost the same for both reactors. Improvement in the fructose productivity for both types of reactors is achieved when compared to the constant optimum temperature of operation. The improvement in the fructose productivity for the plug flow reactor is significant in comparison with the mixed flow reactor.
An Empiric Steady State Model of Lactate Production in Continuous Fermentation with Total Cell Retention
Authors: Richter K. , Nottelmann S.
Published: October 2004

Continuous lactic acid fermentation with total cell recycling was carried out with the strain Lactobacillus paracasei ATB 160111 in a membrane reactor system. The aim of this study was to examine the dependence of lactic acid production and cell mass formation on the hydraulic dilution rate, D, and the availability of both yeast extract and peptone in a modified glucose medium. An experimental design was used and experimental data were obtained, which could be fitted by sigmoidal equations with a high accuracy within the parameter ranges investigated of 0.1 h–1 ≤ D ≤ 0.5 h–1 and 2.5 g/L ≤ peptone/yeast extract ≤ 50 g/L. A steady‐state lactate concentration was established in all tests and a maximum lactate productivity of 26 g/(L × h) was reached at a dilution rate of 0.5 h–1 and a nutrient concentration of 15 g/L. Increasing the concentrations of peptone and yeast extract beyond a value of 15.9 g/L did not lead to an increase in productivity, although total cell mass was accumulated up to 200 g/L. Further examinations showed that only a certain part of the biomass was always active and balanced cell growth was clearly not limited by the lack of any nutrient component in the medium, however, it was affected strongly by product inhibition. A significant decrease in lactic acid yield occurred when the biomass concentration exceeded a value of about 80 g/L. The empiric models used in this study allowed the performance behavior of different strains, for which no biologically well‐founded data are yet known, to be compared. Whether empirical sigmoidal models can be also used for the description of process states in continuous fermentation processes should also be looked into.
Extractive Synthesis of Ethyl‐Oleate Using Alginate Gel Co‐Entrapped Yeast Cells and Lipase Enzyme
Authors: Kiss M.A. , Sefanovits‐Bányai É. , Tóth Á. , Boross L.
Published: October 2004

To synthesize ethyl‐oleate ester, a complex Ca‐alginate gel co‐entrapped system was prepared. The gel beads contained two kinds of biocatalysts (living yeast cells and a lipase enzyme) and various amounts of glucose (100–400 g/L). These alginate beads dispersed directly in pure oleic acid. To follow the bioconversion of the cell growth, the glucose uptake of yeast cells, the concentration of ethanol inside the gel beads and the ethyl‐oleate concentration in oleic acid phase was monitored. The glucose was quantitatively taken up by yeast cells during 24–72 h, depending on the concentration of glucose. After this 24–72‐hour period, the glucose uptake was stopped. In accordance with changes in glucose concentration, the concentration of ethanol and ethyl‐oleate increased rapidly during the first day of fermentation and thereafter slowed down. It is supposed that the inhibitory effect of produced ethanol would be resolved by co‐immobilization of lipase in the same gel particles. Using lipase, one is able to transform ethanol to ethyl‐oleate, which is soluble in oleic acid. According to the data obtained a minimum of 4 U/mL lipase is required to increase ethyl‐oleate production significantly. Summing up it can be concluded that by means of this system a maximum yield of ethanol and ethyl‐oleate was achieved when gel beads containing 100 g/L glucose and 4 U/mL lipase enzyme were used.
Microbial Processes of Heavy Metal Removal from Carbon‐Deficient Effluents in Constructed Wetlands
Authors: Kosolapov D.B. , Kuschk P. , Vainshtein M.B. , Vatsourina A.V. , Wießner A. , Kästner M. , Müller R.A.
Published: October 2004

This paper reviews the main microbial processes involved when toxic metals are removed from wastewater in constructed wetlands. Microbial activity is thought to play a key role in the detoxification of these metals. The paper concentrates on the microbial processes which affect the mobility, the toxicity and bioavailability of metals, namely biosorption, metal sulfide precipitation by sulfate reducers, redox transformations, and methylation, as well as microbe‐plant interactions. These reactions result in either the precipitation and accumulation of metals in wetland soils, or their volatilization and emission into the atmosphere. The possibilities of optimizing the microbially mediated reactions for the development of wetland technology are discussed as a long‐term metal retention strategy.
Chromosomal imbalances detected by array comparative genomic hybridization in human oligodendrogliomas and mixed oligoastrocytomas
Authors: Kitange Gaspar , Misra Anjan , Law Mark , Passe Sandra , Kollmeyer Thomas M. , Maurer Matthew , Ballman Karla , Feuerstein Burt G. , Jenkins Robert B.
Published: October 2004

Loss of heterozygosity and fluorescence in situ hybridization (FISH) studies have shown that deletions of 1p and 19q are highly prevalent in oligodendroglioma. However, these tumors have not been comprehensively screened for other alterations in chromosomal dosage. In this study, we used array‐based comparative genomic hybridization (CGHa) of mapped BAC DNA to screen for such alterations in 31 oligodendrogliomas (20 grade II, 9 grade III, and 2 grade IV) and 4 mixed oligoastrocytomas (1 grade I, 1 grade II, and 2 grade IV). The most frequent aberrations were loss of 1p (17 cases; 49%) and 19q (15 cases; 43%) and combined loss of 1p/19q (13 cases; 37%). In addition, deletion of 4q, 5p, 9p, 10q, 11p, and 13q was observed in 10, 4, 8, 4, 4, and 13 cases, respectively; loss of whole chromosomes 4, 9, and 13 in 4, 1, and 7 cases, respectively; gain of 7p, 8q, 10p, and 11q in 6, 6, 5, and 10 cases, respectively, and gain of whole chromosomes 7 and 11 in 2 patients each. Minimally altered regions detected by CGHa involved chromosome bands 1p36.32, 4q33, 5p15, 8q24, 11p15, and 19q13.3. Univariate analysis of all 35 cases suggested that combined deletion of 1p and 19q is associated with better survival (P= 0.03). In addition, 8q gain in the oligodendrogliomas was strongly associated with poor outcome (P= 0.002). Also associated with poor disease outcome were alterations that had low prevalence in the pure oligodendrogliomas, including loss of 3q, 9q, and 12q and gain of 1p, 8p, and 10q. In summary, in oligodendrogliomas, CGHa was able to detect novel small alterations in chromosomal dosage that had not been previously detected by other methods. In addition, our findings support the hypotheses that oligodendroglioma can be classified into several groups by CGHa analysis and that specific alterations in genetic dosage may have biologic or clinical significance. © 2004 Wiley‐Liss, Inc.