bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistical batch process monitoring using gray models
Authors: Van sprang E. N. M. , Ramaker H.‐J. , Westerhuis J. A. , Smilde A. K. , Wienke D.
Published: February 2005

A complete strategy for monitoring industrial batches processes using gray models is presented including fault detection and fault diagnosis tools. The use of gray models is a novel concept in batch process modeling and monitoring. A gray model is a hybrid model, intermediate between hard (white) process models and soft (black) models, combining the advantages of both approaches. The principles of gray models are explained and it is shown how these models can be constructed. For this purpose an industrial batch process is available that is spectroscopically monitored, and an explanation is provided as to how the spectroscopic measurements are combined with prior process knowledge. To show the versatility of the strategy, two types of gray models are constructed and used for statistical batch process monitoring. The two models are compared and validated for both on‐line monitoring and post‐batch analysis. For the latter, the batch consistency number (BCN) is introduced to have a fast and simple post‐batch analysis. The results show how these models help to detect and diagnose process upsets. The use of gray models for batch process monitoring results in a fast detection of process upsets and a good fault diagnosis. © 2005 American Institute of Chemical Engineers AIChE J, 51: 931–945, 2005
Temporalis function in anthropoids and strepsirrhines: An EMG study
Authors: Hylander William L. , Wall Christine E. , Vinyard Christopher J. , Ross Callum , Ravosa Mathew R. , Williams Susan H. , Johnson Kirk R.
Published: February 2005

The major purpose of this study is to analyze anterior and posterior temporalis muscle force recruitment and firing patterns in various anthropoid and strepsirrhine primates. There are two specific goals for this project. First, we test the hypothesis that in addition to transversely directed muscle force, the evolution of symphyseal fusion in primates may also be linked to vertically directed balancing‐side muscle force during chewing (Hylander et al. [2000] Am. J. Phys. Anthropol. 112:469–492). Second, we test the hypothesis of whether strepsirrhines retain the hypothesized primitive mammalian condition for the firing of the anterior temporalis, whereas anthropoids have the derived condition (Weijs [1994] Biomechanics of Feeding in Vertebrates; Berlin: Springer‐Verlag, p. 282–320). Electromyographic (EMG) activities of the left and right anterior and posterior temporalis muscles were recorded and analyzed in baboons, macaques, owl monkeys, thick‐tailed galagos, and ring‐tailed lemurs. In addition, as we used the working‐side superficial masseter as a reference muscle, we also recorded and analyzed EMG activity of the left and right superficial masseter in these primates. The data for the anterior temporalis provided no support for the hypothesis that symphyseal fusion in primates is linked to vertically directed jaw muscle forces during mastication. Thus, symphyseal fusion in primates is most likely mainly linked to the timing and recruitment of transversely directed forces from the balancing‐side deep masseter (Hylander et al. [2000] Am. J. Phys. Anthropol. 112:469–492). In addition, our data demonstrate that the firing patterns for the working‐ and balancing‐side anterior temporalis muscles are near identical in both strepsirrhines and anthropoids. Their working‐ and balancing‐side anterior temporalis muscles fire asynchronously and reach peak activity during the power stroke. Similarly, their working‐ and balancing‐side posterior temporalis muscles also fire asynchronously and reach peak activity during the power stroke. Compared to these strepsirrhines, however, the balancing‐side posterior temporalis of anthropoids appears to have a relatively delayed firing pattern. Moreover, based on their smaller W/B ratios, anthropoids demonstrate a relative increase in muscle‐force recruitment of the balancing‐side posterior temporalis. This in turn suggests that anthropoids may emphasize the duration and magnitude of the power stroke during mastication. This hypothesis, however, requires additional testing. Furthermore, during the latter portion of the power stroke, the late activity of the balancing‐side posterior temporalis of anthropoids apparently assists the balancing‐side deep masseter in driving the working‐side molars through the terminal portion of occlusion. Am J Phys Anthropol 128:35‐56, 2005. © 2005 Wiley‐Liss, Inc.
Cover Picture: The First μ6‐Peroxide Transition‐Metal Complex: [Ni8(L)12(O2)]2+ (Angew. Chem. Int. Ed. 9/2005)
Authors: Brown Emma J. , Duhme‐Klair Anne‐K. , Elliott Matthew I. , Thomas‐Oates Jane E. , Timmins Phillipa L. , Walton Paul H.
Published: February 2005

Peroxide is frozen in perfect symmetry, which if viewed down the principle axis, resembles that of the snowflake in the cover‐picture background. An unprecedented μ6 peroxide coordination mode is found in an octanuclear nickel complex with near S6 symmetry (core shown in foreground; green Ni, red O). The encapsulation of the peroxide by the nickel cage stabilizes this reactive species. For more details see the Communication by A.‐K. Duhme‐Klair, P. H. Walton, and co‐workers on page 1392 ff. (Background picture reproduced with permission from Prof. K. G. Libbrecht, Caltech.)
Preparation and properties of acid‐treated multiwalled carbon nanotube/waterborne polyurethane nanocomposites
Authors: Kwon Ji‐Yun , Kim Han‐Do
Published: February 2005

Nitric acid treated multiwalled carbon nanotubes (A‐CNTs) were dispersed in a waterborne polyurethane (WBPU) matrix to obtain WBPU/A‐CNT nanocomposite films (99.99/0.01–98.5/1.5) with enhanced thermal, mechanical, and electrical properties. By X‐ray photoelectron spectroscopy (XPS), the oxygen content of the carbon nanotube (CNT) surface was found to increase with increasing acid treatment time. With increasing acid treatment time, the contact angle of the CNT surface was significantly decreased from 15 to 0°. The mean particle sizes of the raw CNT and A‐CNT aqueous solutions were 404.2 and 17.2 nm, respectively, indicating that the acid treatment led to a reduced agglomeration of CNTs. The electrical conductivity of raw CNT was 23 S/cm, and that of A‐CNT significantly increased with increasing acid treatment time up to 30 min and then decreased a little. By dynamic mechanical thermal analysis, the storage modulus and loss tangent peak temperature (the glass‐transition temperature) of the WBPU/A‐CNT nanocomposites were found to increase with increasing A‐CNT content. The initial tensile moduli and tensile strengths of the nanocomposite film with 1.5 wt % loading of A‐CNT were enhanced by about 19 and 12%, respectively, compared to the corresponding values for the original WBPU film. The WBPU/A‐CNT1.5 nanocomposite film containing 1.5 wt % of A‐CNT exhibited a conductivity of 1.2 × 10−4 S/cm, which was nearly eight orders of magnitude higher that of the WBPU film (2.5 × 10−12 S/cm). The antistatic half‐life (τ1/2) of the WBPU film was about 110 s, indicating that pure the WBPU film was a typical electrostatic material. However, those of the WBPU/A‐CNT nanocomposites decreased exponentially with increasing A‐CNT content. The WBPU/A‐CNT1.5 sample, containing 1.5 wt % of A‐CNT and with a τ1/2 of 1 s, had good antistatic properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 595–604, 2005
Water flux through blends from waste materials: Cellulose acetate (from sugar cane bagasse) with polystyrene (from plastic cups)
Authors: Filho Guimes Rodrigues , da Silva Ricardo Chagas , da Silva Meireles Carla , de Assunção Rosana Maria Nascimento , Otaguro Harumi
Published: February 2005

In the present work we blended cellulose acetate (taken from sugar cane bagasse) (CA) with polystyrene (taken from postconsumer plastic cups) (PS). The blends were produced in the following ratios (w/w) of the polymers: CA 50%/PS 50%, CA 90%/PS 10%, and CA 10%/PS 90%, using dichloromethane as solvent. The blends were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and wide‐angle X‐ray diffraction. The results show that the presence of polystyrene hinders the organization of regions responsible for the crystallinity originally existing in pure cellulose acetate. We also made measurements of water flux through blends, using the Payne cup technique. The flux properties were compared with those obtained for commercial membranes by Osmonix: nanofiltration (SG) and reverse osmosis (CG). The results show that the blend CA 90%/PS 10% presents water vapor flux comparable with that of commercial membranes for nanofiltration (SG). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 516–522, 2005
Graphite–epoxy graded material by centrifugation
Authors: Hashmi S. A. R. , Dwivedi U. K. , Jain D. , Naik Ajay , Chand Navin
Published: February 2005

A graded distribution of graphite particles in epoxy resin matrix was obtained using a centrifugation technique. By varying the centrifugation time the graded profile could be effectively controlled. Scanning electron microscopy and optical microscopy revealed the graded dispersion of graphite particles in the epoxy matrix, which is sensitive to centrifugation time. Electrical or wear properties can accurately estimate the property profile of graded material. The abrasive wear test also provided a quick estimation of the extent of gradient formed in the sample. The increased centrifugation time increased the compaction of graphite particles in the graphite‐rich phase of graded material that could be correlated with the increased capacitance of the sample. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 550–556, 2005
Poly(etherurethane) anionomers with azobenzene carboxylate groups: Synthesis and properties
Authors: Buruiana Tinca , Buruiana E. C.
Published: February 2005

A new diol with a one‐sided azobenzene‐carboxyl group was prepared to be used for photosensible polymers synthesis. Azobenzene carboxyl containing polyurethane based on poly(tetramethylene oxide) diol of 2000 average molecular weight, 2,4‐tolylene diisocyanate, and the mentioned azo diol, was obtained and characterized. Upon neutralization the acid form with metal acetate (Li+1, Ca+2) or triethylamine azo carboxylate anionomers with an improved phase separation were obtained. Viscometric measurements of diluted dimethylformamide solutions exhibited evidence of polyelectrolyte behavior. Some aspects of the trans‐cis photoisomerization have been examined to design in future various dyed aqueous dispersions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 577–582, 2005
Problems with Existing Procedures to Calculate Exact Unconditional P‐Values for Non‐Inferiority/Superiority and Confidence Intervals for Two Binomials and How to Resolve Them
Authors: Röhmel Joachim
Published: February 2005

Recently several papers have been published that deal with the construction of exact unconditional tests for non‐inferiority and confidence intervals based on the approximative unconditional restricted maximum likelihood test for two binomial random variables. Soon after the papers have been published the commercially available software for exact tests StatXact has incorporated the new methods. There are however gaps in the proofs which since have not been resolved adequately. Further it turned out that the methods for testing non‐inferiority are not coherent and test for non‐inferiority can easily come to different conclusions compared to the confidence interval inclusion rule. In this paper, a proposal is made how to resolve the open problems. Berger and Boos (1994) developed the confidence interval method for testing equality of two proportions. StatXact (Version 5) has extended this method for shifted hypotheses. It is shown that at least for unbalanced designs (i.e. largely different sample sizes) the Berger and Boos method can lead to controversial results. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mild and Efficient Copper‐Catalyzed Cyanation of Aryl Iodides and Bromides
Authors: Cristau Henri‐Jean , Ouali Armelle , Spindler Jean‐Francis , Taillefer Marc
Published: February 2005

An efficient copper‐catalyzed cyanation of aryl iodides and bromides is reported. Our system combines catalytic amounts of both copper salts and chelating ligands. The latter, which have potential nitrogen‐ and/or oxygen‐binding sites, have never previously been used in this type of reaction. A protocol has been developed that enables the cyanation of aryl bromides through the copper‐catalyzed in situ production of the corresponding aryl iodides using catalytic amounts of potassium iodide. Aryl nitriles are obtained in good yields and excellent selectivities in relatively mild conditions (110 °C) compared with the Rosenmund–von Braun cyanation reaction. Furthermore, the reaction is compatible with a wide range of functional groups including nitro and amino substituents. The protocol reported herein involves two main innovations: the use of catalytic amounts of ligands and the use of acetone cyanohydrin as the cyanating agent in copper‐mediated cyanation reactions.
Soluble Oligoaramide Precursors—A Novel Class of Building Blocks for Rod–Coil Architectures
Authors: Abbel Robert , Frey Holger , Schollmeyer Dieter , Kilbinger Andreas F. M.
Published: February 2005

A new synthetic route is described that allows the reversible conversion of the inherently insoluble oligo‐p‐benzamides into soluble materials through the formation of imidoyl chlorides. Syntheses of the corresponding dimer, trimer, and tetramer are reported; these compounds can easily be purified by crystallization and are accessible on the multigram scale. Structural proof was obtained by single‐crystal X‐ray structures of the trimer and tetramer precursors. They can be selectively functionalized into amides or esters at the terminal carboxylic acid group followed by hydrolysis of the imidoyl chlorides to the parent amides. This new class of compounds gives access to strongly aggregating rigid rodlike materials in few synthetic steps, as is demonstrated by the preparation of poly(ethylene glycol)‐co‐oligo(p‐benzamide) rod–coil block copolymers.
Enantioselective Syntheses and Configuration Assignments of γ‐Chiral Butenolides from Plagiomnium undulatum: Butenolide Synthesis from Tetronic Acids
Authors: Kapferer Tobias , Brückner Reinhard , Herzig Axel , König Wilfried A.
Published: February 2005

Both enantiomers of the γ‐chiral α,β‐dimethylated butyrolactones nat‐1 and nat‐2 from the moss Plagiomnium undulatum were synthesized stereoselectively through butenolides and tetronic acids, respectively. The configuration of the natural products was determined by GLC comparisons with mono(3‐O‐acetyl‐6‐O‐tert‐butyldimethylsilyl‐2‐O‐methyl)hexakis(6‐O‐tert‐butyldimethylsilyl‐2,3‐di‐O‐methyl)‐β‐cyclodextrin as a stationary phase.
Synthesis and Structure of an Unexpected Platinum π Complex Formed from Substituted 1,4‐Diamino Ligands through an Elimination Process
Authors: Gay Marina , Montaña Ángel M. , Moreno Virtudes , Font‐Bardia Mercè , Solans Xavier
Published: February 2005

An unusual reactivity of cis‐1,2‐bis[(N,N‐dimethylamino)methyl] cyclohexane with PtCl2 was observed, resulting in the formation of a platinum(II) π‐olefin complex instead of the conventional square‐planar cis PtII coordination complex with the diamino ligand. This behavior was interpreted on the basis of the steric hindrance of the dimethylamino groups whose electron lone pairs are barely accessible to a platinum atom, which can make it difficult for both dimethylamino groups to bind platinum at the same time. This complex has been physically and spectroscopically characterized and its structure has been confirmed by using X‐ray diffraction analyses on single crystals.
Binding of lipopeptide to CD14 induces physical proximity of CD14, TLR2 and TLR1
Authors: Manukyan Maria , Triantafilou Kathy , Triantafilou Martha , Mackie Alan , Nilsen Nadra , Espevik Terje , Wiesmüller Karl‐Heinz , Ulmer Artur J. , Heine Holger
Published: February 2005

Lipoproteins or lipopeptides (LP) are bacterial cell wall components detected by the innate immune system. For LP, it has been shown that TLR2 is the essential receptor in cellular activation. However, molecular mechanisms of LP recognition are not yet clear. We used a FLAG‐labeled derivative of the synthetic lipopeptide N‐palmitoyl‐S‐[2,3‐bis(palmitoyloxy)‐(2R,S)‐propyl]‐(R)‐cysteinyl‐seryl‐(lysyl)3‐lysine (Pam3CSK4) to study the roles of CD14, TLR2 and TLR1 in binding and signaling of LP and their molecular interactions in human cells. The activity of Pam3CSK4‐FLAG was TLR2 dependent, whereas the binding was enabled by CD14, as evaluated by flow cytometry and confocal microscopy. Using FRET and FRAP imaging techniques to study molecular associations, we could show that after Pam3CSK4‐FLAG binding, CD14 and Pam3CSK4‐FLAG associate with TLR2 and TLR1, and TLR2 is targeted to a low‐mobility complex. Thus, LP binding to CD14 is the first step in the LP recognition, inducing physical proximity of CD14 and LP with TLR2/TLR1 and formation of the TLR2 signaling complex.
Graft rejection mediated by CD4+ T cells via indirect recognition of alloantigen is associated with a dominant Th2 response
Authors: Csencsits Keri , Wood Sherri Chan , Lu Guanyi , Magee John C. , Eichwald Ernst J. , Chang Cheong‐Hee , Bishop D. Keith
Published: February 2005

CD4+ T cells that respond to indirectly presented alloantigen have been shown to mediate chronic rejection, however, the role of the indirect pathway in acute rejection has yet to be completely elucidated. To this end, BALB/c or C57BL/6 mice were depleted of CD8+ T cells and transplanted with class II transactivator (CIITA)‐deficient cardiac allografts, which cannot directly present class II alloantigens to CD4+ T cells. In this manner, the rejection response by CD4+ cells was forced to rely upon the indirect recognition pathway. When not depleted of CD8+ cells, both BALB/c and C57BL/6 mice rejected CIITA–/– allografts and a polarized Th1 response was observed. In contrast, when BALB/c recipients of CIITA–/– allografts were depleted of CD8+ T cells, the grafts were acutely rejected and a strong Th2 response characterized by eosinophil influx into the graft was observed. Interestingly, CD8‐depleted C57BL/6 recipients of CIITA–/– allografts did not acutely reject their transplants and a Th2 response was not mounted. These findings indicate that CD4+ T cells responding to indirectly presented alloantigens mediate graft rejection in a Th2‐dominant manner, and provide further evidence for the role of Th2 responses in acute graft rejection.
CCL22‐induced responses are powerfully enhanced by synergy inducing chemokines via CCR4: evidence for the involvement of first β‐strand of chemokine
Authors: Sebastiani Silvia , Danelon Gabriela , Gerber Basil , Uguccioni Mariagrazia
Published: February 2005

In an attempt to clarify how cells integrate the signals provided by multiple chemokines expressed during inflammation, we have uncovered a novel mechanism regulating leukocyte trafficking. Our data indicate that the concomitant exposure to CCR4 agonists and CXCL10/IP‐10 strongly enhances the chemotactic response of human T lymphocytes. This enhancement is synergistic rather than additive and occurs via CCR4 since it persists after CXCR3 blockade. Besides chemotaxis, other cellular responses are enhanced upon stimulation of CCR4‐transfected cells with CCL22/MDC plus CXCL10. Several other chemokines in addition to CXCL10 were able to increase CCL22‐mediated chemotaxis. The first β‐strand of the chemokine structure is highly and specifically implicated in this phenomenon, as established using synergy‐inducing and non‐synergy‐inducing chimeric chemokines. As shown in situ for skin from atopic and allergic contact dermatitis patients, this organ becomes the ideal environment in which skin‐homing CCR4+ T lymphocytes can accumulate under the stimulus offered by CCR4 agonists, together with the synergistic chemokines that are concomitantly expressed. Overall, our results indicate that chemokine‐induced synergism strengthens leukocyte recruitment towards tissues co‐expressing several chemokines.
Ozonolyses of Enantiopure 4‐Alkoxy‐3,6‐dihydro‐2H‐1,2‐oxazines:An Expedient Route to Functionalized α‐Amino‐β‐hydroxy Esters
Authors: Helms Matthias , Reißig Hans‐Ulrich
Published: February 2005

Ozonolysis and subsequent in situ acylation/base treatment converted the enantiopure carbohydrate‐derived 1,2‐oxaz‐ines 1, 5, 8 (either syn‐ or anti‐configured) and anti‐11 into the highly functionalized α‐amino‐β‐hydroxy esters 2, 6, 9 and 12 in moderate to good yields. Ketals of 5‐hydroxylated 1,2‐oxazines (e.g., syn‐3) were formed as side products in most cases; the reactions of precursors syn‐ and anti‐8 even provided the ketals syn‐ or anti‐10 as major components. The synthesized functionalized amino esters are valuable intermediates, as demonstrated by the subsequent transformation of anti‐2 into the enantiopure building blocks 13–15. Since precursor 1,2‐oxazines were prepared via lithiated alkoxyallenes, the latter species were serving as formyl ester anion equivalents. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Capillary electrophoresis direct enantioseparation of aromatic amino acids based on mixed chelate‐inclusion complexation of aminoethylamino‐β‐cyclodextrin
Authors: Wu Bidong , Wang Qingqing , Liu Qin , Xie Jianwei , Yun Liuhong
Published: February 2005

6A‐(2‐Aminoethylamino)‐6A‐deoxy‐β‐cyclodextrin (CDen) was synthesized and formed a binary complex with Cu(II) which was shown to be an effective chiral selector for separation of underivatized amino acid enantiomers in capillary electrophoresis (CE). Moreover, the chiral resolution was greatly enhanced by the presence of polyethyl glycol (PEG) and tert‐butyl alcohol in the running buffer. The optimum experimental conditions were 20 mmol/L CDen, 20 mmol/L CuSO4·5H2O, 5.0 mg/mL PEG20000 and 1.0% v/v tert‐butyl alcohol, pH 5.80. With the proposed method, the four selected aromatic chiral amino acid pairs were separated in less than 15 min.
Chiral recognition ability of an (S)‐naproxen‐ imprinted monolith by capillary electrochromatography
Authors: Xu Yan‐Li , Liu Zhao‐Sheng , Wang He‐Fang , Yan Chao , Gao Ru‐Yu
Published: February 2005

The racemic naproxen was selectively recognized by capillary electrochromatography (CEC) on an (S)‐naproxen‐imprinted monolith, which was prepared by an in situ thermal‐initiated polymerization. The recognition selectivity of a selected monolith strictly relied on the CEC conditions involved. The factors that influence the imprinting selectivity as well as the electroosmotic flow (EOF), including the applied voltage, organic solvent, salt concentration and pH value of the buffer, column temperature, and surfactant modifiers were systematically studied. Once the column was prepared, the experiment results showed that the successful chiral recognition was dependent on CEC variables. For example: the recognition could be observed in acetonitrile and ethanol electrolytes, while methanol and dimethyl sulfoxide (DMSO) electrolytes had no chiral recognition ability. The buffer with pH values of 2.6 or 3.0 at a higher salt concentration had chiral recognition ability. Column temperatures of 25–35°C were optimal. Three surfactants, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and polyoxyethylene sorbitan monolaurate (Tween 20), can improve the recognition. Baseline resolution was obtained under optimized conditions and the column efficiency of the later eluent (S)‐naproxen was 90 000 plates/m.
Electrochromatographic evaluation of a silica monolith capillary column for separation of basic pharmaceuticals
Authors: Xie Chuanhui , Hu Jiwei , Xiao Hua , Su Xingye , Dong Jing , Tian Ruijun , He Zhike , Zou Hanfa
Published: February 2005

A silica‐based monolithic capillary column was prepared via a sol‐gel process. The continuous skeleton and large through‐pore structure were characterized by scanning electron microscopy (SEM). The native silica monolith has been successfully employed in the electrochromatographic separation of β‐blockers and alkaloids extracted from traditional Chinese medicines (TCMs). Column efficiencies greater than 250 000 plates/m for capillary electrochromatography (CEC) separation of basic compounds were obtained. It was observed that retention of basic pharmaceuticals on the silica monolith was mainly contributed by a cation‐exchange mechanism. Other retention mechanisms including reversed‐phase and normal‐phase mechanisms and electrophoresis of basic compounds also played a role in separation. A comparison of the differences between CEC and capillary zone electrophoresis (CZE) separation was also discussed.
Enantioseparation of chiral allenic acids by micellar electrokinetic chromatography with cyclodextrins as chiral selector
Authors: Wang Zhaoyan , Tang Zhongmei , Gu Zhenhua , Hu Zhide , Ma Shengming , Kang Jingwu
Published: February 2005

Enantioseparation of chiral aryl allenic acids by micellar electrokinetic chromatography (MEKC) with cyclodextrins (CDs) as chiral selectors was described. The screen of chiral selectors (β‐CD, γ‐CD, and hydroxypropyl (HP)‐γ‐CD) showed that the enantioseparation was not only dependent on the type of CD but also the presence of 2‐propanol in the buffer. In order to optimize the operational parameters, the effect of the concentration of CDs, sodium dodecyl sulfate (SDS), and 2‐propanol, as well as the buffer ionic strength and pH on enantioseparation were studied. It was proved that the concentration of CDs, 2‐propanol, and the buffer ionic strength were the critical parameters. Under optimal conditions, baseline separations of all seven allenic acid enantiomers were achieved. Furthermore, the method validation in terms of repeatability, linearity, limit of detection (LOD), and limit of quantitation (LOQ) were performed. Using the present method, the optical purity of a nonracemic sample with the enantiomeric excess (e.e.%) value of 99.65% was determined.
Separation and on‐column preconcentration of some nonsteroidal anti‐inflammatory drugs by microemulsion electrokinetic capillary chromatography using high‐speed separations
Authors: Macià Alba , Borrull Francesc , Calull Marta , Aguilar Carme
Published: February 2005

Various strategies have been investigated for separating a group of nonsteroidal anti‐inflammatory drugs (NSAIDs) by microemulsion electrokinetic capillary chromatography (MEEKC) using high‐speed separations. The parameters that of affect the separation, such as the nature of the oil droplet and the buffer, and the surfactant concentration have been studied. In addition, several organic solvents were used to decrease the retention of the analytes in the oil droplet phase and to improve the resolution of the NSAIDs. The optimum microemulsion background electrolyte (BGE) solution made of 0.8% w/w ethyl acetate, 6.6% w/w butan‐1‐ol, 6.0% w/w acetonitrile, 1.0% w/w sodium dodecyl sulfate (SDS), and 85.6% w/w of 10 mM sodium tetraborate at pH 9.2 resolved the drugs within 8 min. The short‐end injection procedure is an alternative for reducing the analysis time. When this procedure was used, the microemulsion BGE solution consisted of 0.8% w/w ethyl acetate, 6.6% w/w butan‐1‐ol, 17.0% w/w methanol, 1.0% w/w SDS, and 74.6% w/w of 10 mM sodium tetraborate, pH 9.2, and the NSAIDs were separated within 3 min. The reversed electrode polarity stacking mode (REPSM) technique was applied to the on‐line concentration of the NSAIDs. In this technique, the sample matrix was pumped out of the capillary using a polarity‐switching step. When this technique was applied, the sensitivity was enhanced up to 40‐fold and the limits of detection (LODs) were in the low μg·L‐1 levels.
Amino acid analysis by micellar electrokinetic chromatography with laser‐induced fluorescence detection: Application to nanolitre‐volume biological samples from Arabidopsis thaliana and Myzus persicae
Authors: Zhu Xunlin , Shaw P. Nicholas , Pritchard Jeremy , Newbury John , Hunt Emma J. , Barrett David A.
Published: February 2005

Amino acids were derivatised with 4‐fluoro‐7‐nitrobenzo‐2,1,3‐oxadiazol (NBD‐F), separated by micellar electrokinetic chromatography (MEKC), and detected by argon‐ion (488 nm) laser‐induced fluorescence. The optimised MEKC background electrolyte conditions were: 40 mM sodium cholate, 5 mM β‐cyclodextrin in 20 mM aqueous borate buffer, pH 9.1, with 7% v/v acetonitrile. Using these conditions, 19 amino acids were separated within 17 min. The limits of detection were in the range of 7.6–42.2 pmol/mL and limits of quantitation from 0.05–0.14 nmol/mL. The method was systematically validated for injection volume error, migration time variation, calibration linearity, accuracy, precision, and recovery. Nanolitre volume samples of phloem sap of individual sieve element cells from the plant Arabidopsis thaliana and honeydew from the aphid Myzus persicae were directly analysed with this method. Quantitative amino acid concentrations in these two biological matrices were profiled for the first time. This method is particularly important because it allows the complete profile of the amino acids obtained from individual phloem elements, allowing cell to cell and plant to plant variation to be quantified, which to date has not been possible with Arabidopsis thaliana.
Language processing within the human medial temporal lobe
Authors: Meyer Patric , Mecklinger Axel , Grunwald Thomas , Fell Juergen , Elger Christian E. , Friederici Angela D.
Published: February 2005

Although the hippocampal formation is essential for verbal memory, it is not fully understood how it contributes to language comprehension. We recorded event‐related potentials (ERPs) directly from two substructures of the medial temporal lobe (MTL), the rhinal cortex and the hippocampus proper, while epilepsy patients listened to sentences that either were correct or contained semantic or syntactic violations. Semantic violations elicited a large negative ERP response peaking at ∼400 ms in the rhinal cortex. In contrast, syntactically incorrect sentences elicited a negative deflection of 500–800 ms in the hippocampus proper. The results suggest that functionally distinct aspects of integration in language comprehension are supported by different MTL structures: the rhinal cortex is involved in semantic integration, whereas the hippocampus proper subserves processes of syntactic integration. An analysis of phase synchronization within the gamma band between rhinal and hippocampal recording sites showed that both of the above‐mentioned ERP components were preceded by an increase of phase synchronization. In contrast to these short phasic increases of phase synchronization in both violation conditions, correct sentences were associated with a long‐lasting synchronization in a late time window, possibly reflecting the integration of semantic and syntactic information as required for normal comprehension. © 2005 Wiley‐Liss, Inc.
Effect of sucrose on nisin production in batch and fed‐batch culture by Lactococcus lactis
Authors: Lv Wenhua , Cong Wei , Cai Zhaoling
Published: February 2005

The effects of sucrose on cell growth and nisin production by Lactococcus lactis were investigated in batch and pH feed‐back controlled fed‐batch cultures. In batch cultures, nisin titer reached its maximum, 2658 IU cm−3, at the initial sucrose concentration of 30 g dm−3. With sucrose concentrations higher than 30 g dm−3, nisin production decreased while the biomass was not influenced significantly. By using the pH feed‐back controlled method, residual sucrose concentration could be controlled well in fed‐batch cultures and three conditions (sucrose maintained at 2, 16, 20 g dm−3, respectively) were evaluated. Maintaining a low sucrose concentration at 2 g dm−3 during feeding favored nisin biosynthesis, and the maximum nisin titer obtained was 4961 IU cm−3 compared with 3370 IU cm−3 (16 g sucrose dm−3)and 3498 IU cm−3 (20 g sucrose dm−3), respectively. Copyright © 2005 Society of Chemical Industry
Analysis of neutral oligosaccharides for structural characterization by matrix‐assisted laser desorption/ionization quadrupole ion trap time‐of‐flight mass spectrometry
Authors: Ojima Noriyuki , Masuda Katsuyoshi , Tanaka Koichi , Nishimura Osamu
Published: February 2005

We have acquired multi‐stage mass spectra (MSn) of four branched N‐glycans derived from human serum IgG by matrix‐assisted laser desorption/ionization quadrupole ion trap time‐of‐flight mass spectrometry (MALDI‐QIT‐TOF‐MS) in order to demonstrate high sensitivity structural analysis. [M + H]+ and [M + Na]+ ions were detected in the positive mode. The detection limit of [M + Na]+ in MS/MS and MS3 measurements for structural analysis was found to be 100 fmol, better than that for [M + H]+. The [M + H]+ ions subsequently fragmented to produce predominantly a Y series of fragments, whereas [M + Na]+ ions fragmented to give a complex mixture of B and Y ions together with some cross‐ring fragments. Three features of MALDI‐QIT‐CID fragmentation of [M + Na]+ were cleared by the analysis of MS/MS, MS3 and MS4 spectra: (1) the fragment ions resulting from the breaking of a bond are more easily generated than that from multi‐bond dissociation; (2) the trimannosyl–chitobiose core is either hardly dissociated, easily ionized or it is easy to break a bond between N‐acetylglucosamine and mannose; (3) the fragmentation by loss of only galactose from the non‐reducing terminus is not observed. We could determine the existence ratios of candidates for each fragment ion in the MS/MS spectrum of [M + Na]+ by considering these features. These results indicate that MSn analysis of [M + Na]+ ions is more useful for the analysis of complicated oligosaccharide structures than MS/MS analysis of [M + H]+, owing to the higher sensitivity and enhanced structural information. Furthermore, two kinds of glycans, with differing branch structures, could be distinguished by comparing the relative fragment ion abundances in the MS3 spectrum of [M + Na]+. These analyses demonstrate that the MSn technology incorporated in MALDI‐QIT‐TOF‐MS can facilitate the elucidation of structure of complex branched oligosaccharides. Copyright © 2005 John Wiley & Sons, Ltd.
Rapid characterization of Bacillus spores targeting species‐unique peptides produced with an atmospheric pressure matrix‐assisted laser desorption/ionization source
Authors: Pribil Patrick A. , Patton Elizabeth , Black Gavin , Doroshenko Vladimir , Fenselau Catherine
Published: February 2005

New and improved strategies are eagerly sought for the rapid identification of microorganisms, particularly in mixtures. Mass spectrometry remains a powerful tool for this purpose. Small acid‐soluble proteins (SASPs), which are relatively abundant in Bacillus spores, represent potential biomarkers for species characterization. Despite sharing extensive sequence homology, these proteins differ sufficiently in sequence for discrimination between species. This work focuses on the differences in sequence between SASPs from various Bacillus species. Compilation of SASP sequences from protein database searches, followed by in silico trypsin digestion and analysis of the resulting fragments, identified several species‐specific peptides that could be targeted for analysis using mass spectrometry. This strategy was tested and found to be successful in the characterization of Bacillus spores both from individual species and in mixtures. Analysis was performed using an ion trap mass spectrometer with an atmospheric pressure MALDI source. This instrumentation offers the advantage of increased speed of analysis and accurate precursor ion selection for tandem mass spectrometric analysis compared with vacuum matrix‐assisted laser desorption/ionization and time‐of‐flight instruments. The identification and targeting of species‐specific peptides using this type of instrumentation offers a rapid, efficient strategy for the identification of Bacillus spores and can potentially be applied to different microorganisms. Copyright © 2005 John Wiley & Sons, Ltd.
CHASE, a charge‐assisted sequencing algorithm for automated homology‐based protein identifications with matrix‐assisted laser desorption/ionization time‐of‐flight post‐source decay fragmentation data
Authors: Raucci Giuseppe , Gabrielli Meri , Novelli Sabrina , Picariello Gianluca , Collins Stephen H.
Published: February 2005

We describe CHASE, a novel algorithm for automated de novo sequencing based on the mass spectrometric (MS) fragmentation analysis of tryptic peptides. This algorithm is used for protein identification from sequence similarity criteria and consists of four steps: (1) derivatization of tryptic peptides at the N‐terminus with a negatively charged reagent; (2) post‐source decay (PSD) fragmentation analysis of peptides; (3) interpretation of the mass peaks with the CHASE algorithm and reconstruction of the amino acid sequence; (4) transfer of these data to software for protein identifications based on sequence homology (Basic Local Alignment Search Tool, BLAST). This procedure deduced the correct amino acid sequence of tryptic peptide samples and also was able to deduce the correct sequence from difficult mass patterns and identify the amino acid sequence. This allows complete automation of the process starting from MS fragmentation of complex peptide mixtures at low concentration (e.g. from silver‐stained gel bands) to identification of the protein. We also show that if PSD data are collected in a single spectrum (instead of the segmented mode offered by conventional matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) instrumentation), the complete workflow from MS‐PSD data acquisition to similarity‐based identification can be completely automated. This strategy may be applied to proteomic studies for protein identification based on automated de novo sequencing instead of MS or tandem MS patterns. We describe the Charge Assisted Sequencing Engine (CHASE) algorithm, the working protocol, the performance of the algorithm on spectra from MALDI‐TOFMS and the data comparison between a TOF and a TOF–TOF instrument. Copyright © 2005 John Wiley & Sons, Ltd.
Determination of micelle mass by electrospray ionization mass spectrometry
Authors: Nohara Daisuke , Kajiura Takatomo , Takeda Koji
Published: February 2005

By electrospray ionization (ESI) mass spectrometry, micelle solutions of sodium cholate were investigated in detail in the presence and absence of ethanol. The average aggregation number could be evaluated from the spectra acquired under conditions where soft collisions adequate to measure the micelle solution were induced, and the value agreed well with that obtained previously by other methods. From the dependence on ethanol content, it was also found that the average aggregation number in aqueous solution without organic solvent could be reliably estimated. The ESI method proved to be a useful tool for determining the micelle mass in the original aqueous phase. Copyright © 2005 John Wiley & Sons, Ltd.
Quantification of urinary N‐acetyl‐S‐ (propionamide)cysteine using an on‐line clean‐up system coupled with liquid chromatography/tandem mass spectrometry
Authors: Li Chien‐Ming , Hu Chiung‐Wen , Wu Kuen‐Yuh
Published: February 2005

Acrylamide has been reported to be present in high‐temperature processed foods and normal processed food intake could lead to significant acrylamide exposure. Acrylamide in vivo can be conjugated with glutathione in the presence of glutathione transferase. This conjugation product is further metabolized and excreted as N‐acetyl‐S‐(propionamide)cysteine (NASPC) in the urine. NASPC could be considered a biomarker for acrylamide exposure. The objective of this study was to develop a highly specific, rapid and sensitive method to quantify urinary NASPC, serving as a biomarker for acrylamide exposure assessment. Isotope‐labeled [13C3]NASPC was successfully synthesized and used as an internal standard. This urine mixture was directly analyzed using a newly developed liquid chromatographic/tandem mass spectrometric method coupled with an on‐line clean‐up system. The detection limit for this method was estimated as <5 µg l−1(0.4 pmol) on‐column. The method was applied to measure the urinary level of NASPC in 70 apparently health subjects. The results showed that the NASPC urinary level was highly associated with smoking. Smokers had a significantly higher urinary NASPC level (135 ± 88 µg g−1 creatinine) than non‐smokers (76 ± 30 µg g−1 creatinine). A highly sensitive and selective LC/MS/MS isotope dilution method was successfully established. With an on‐line clean‐up system, this system is capable of routine high‐throughput analysis and accurate quantitation of NASPC in urine. This could be a useful tool for health surveillance for acrylamide exposure in a population for future study. Copyright © 2005 John Wiley & Sons, Ltd.
Gas‐phase ion chemistry in XH4C3H4ZH3 (XSi, Ge; ZN, P) mixtures
Authors: Operti Lorenza , Rabezzana Roberto , Turco Francesca , Vaglio Gian Angelo
Published: February 2005

The gas‐phase ion chemistry of silane–allene–ammonia, germane–allene (or propyne)–ammonia (or phosphine) systems was studied by ion trap mass spectrometry. Reaction sequences were determined and rate constants were measured for the main processes observed. The mixture containing silane displays higher reactivity with respect to that with germane. Comparison with analogous systems provides useful information about the reactivity of different hydrocarbon molecules and the different affinities of silicon and germanium towards nitrogen and phosphorus. The most interesting product ions observed are those containing Si (or Ge), C and N (or P) elements together, as these ion species may be considered precursors of doped amorphous carbides, which are widely used in semiconductor devices. Copyright © 2005 John Wiley & Sons, Ltd.
Electrolytic electrospray ionization mass spectrometry of quaterthiophene‐bridged bisporphyrins: beyond the identification tool
Authors: Rondeau David , Rogalewicz Françoise , Ohanessian Gilles , Levillain Eric , Odobel Fabrice , Richomme Pascal
Published: February 2005

Several quaterthiophene‐bridged bisporphyrins were analyzed by electrospray ionization mass spectrometry (ESI‐MS). The active centers of these molecular assemblies are two porphyrins moieties complexed (Z) or not (H) with a metal ion, typically Zn2+, and the spacer is a quaterthiophene. The two end‐groups were chemically linked to the quaterthiophene spacers by (i) a CC single bond, (ii) a trans double bond or (iii) a triple bond. The formation of charged species either by protonation ([M + H]+ and [M + 2H]2+) or electron(s) loss (M+ and M2+), account for the occurrence of electrochemical processes in the basic operation of an electrospray source acting in a non‐aqueous solvent. The nature of the observed charged species is correlated with the electro‐oxidation properties and proton production by electro‐oxidation of residual water. The occurence of these electrochemical reaction is proposed when the electroactivity of the electrosprayed substrates is not sufficient to support the current demand of the ESI source. In this way, the results obtained from the analysed series suggest the occurrence of such a process when the interfacial potential of the metal capillary reaches a value of 0.75 V vs Ag/AgCl. The results of theoretical calculations confirm the importance of the ionization energy with regard to the protonation energy in the course of the ionization reaction. The structural differences at the porphyrin–linker junctions lead to significantly smaller ionization energy in the case of the trans double bond. The MS observation of discharged dimers from molecular assemblies, including two complexed porphyrins ZZ or two free bases HH as end‐group and a triple bond as the quaterthiophene–bisporphyrin junction, indicates together with molecular modelling (carried out at the semi‐empirical PM3 level), that the planar and symmetric structures favour stacking. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis of the chiral composition of a carbon nanotube surface by means of second harmonic generation
Authors: De Dominicis L. , Fantoni R. , Botti S. , Ciardi R. , Asilyan L. , Fiori A. , Orlanducci S.
Published: February 2005

The second‐order susceptibility tensor χ(2)(2ω;ω, ω) of a carbon nanotube (CNT) surface was determined as a function both of the average tube orientation and CNT topology distribution. The transformation properties of the hyperpolarizability β tensor, as rooted in the CNT isogonal symmetry point group, make non‐vanishing only the chiral component of χ(2)(2ω;ω, ω), thus denying second harmonic generation (SHG) in racemic samples. Nevertheless, the rupture of the CNT spatial symmetry due to local deformations and to finite size can act as a source for SHG even in racemic samples. The study of SHG polarization and of the anisotropic dependence of the signal intensity on the angle Ω between the surface normal and the exciting laser beam direction are proposed as methods to discriminate between the two contributions. An experimental test of such a statement was performed on a sample grown by the laser annealing technique. A massive presence of chiral CNTs with strong local deformations was revealed by the low‐ and medium‐wavenumber Raman spectra measured on the sample. The SHG polarization and the anisotropic dependence of the signal intensity as a function of Ω were studied experimentally, allowing the racemic nature of the investigated sample to be elucidated. Copyright © 2005 John Wiley & Sons, Ltd.
Refined theory of two‐photon processes accounting for virtual electric quadrupole and magnetic dipole transitions
Authors: Egorova N. , Kouzov A. , Chrysos M. , Rachet F.
Published: February 2005

Two‐photon transition amplitudes, accounting for virtual double electric dipole–electric quadrupole (E1, E2) and electric dipole–magnetic dipole (E1, M1) transitions, are derived for isotropic molecular ensembles. The new‐type non‐resonant Raman scattering is shown to appear from the interfering emission fields generated by multipoles (electric dipole, electric quadrupole and magnetic dipole) induced on a scattering particle. The interference is found to affect strongly the angular distribution and polarization characteristics of the scattered radiation, damping the forward scattering while enhancing the backward scattering. When the excitation frequency approaches an absorption resonance, the interference features are shown to disappear from the Raman spectra. In the off‐resonance case, the Raman cross‐section equations for gases of linear and spherical (Td) molecules are elaborated in terms of the mixed electronic polarizabilities expressed via their invariants in the molecule‐fixed frame. Copyright © 2005 John Wiley & Sons, Ltd.
Photo‐fragment excitation spectroscopy (PHOFEX) by DFWM and LIF: propensities for H2CO → HCO + H near the So threshold
Authors: Tulej M. , Knopp G. , Beaud P. , Gerber T. , Radi P. P.
Published: February 2005

A novel technique for photo‐fragment excitation spectroscopy (PHOFEX) is introduced by applying resonant‐enhanced degenerate four‐wave mixing (DFWM) and laser‐induced fluorescence (LIF). The method is applied to investigate the dynamics of the radical channel decomposition of H2CO. The DFWM configuration is used to excite H2CO to an energy level close to the threshold for dissociation to radical products on the S0 potential energy surface. Simultaneously, LIF is employed to detect the nascent HCO fragments. PHOFEX spectra are recorded by tuning the DFWM photon energy near the dissociation threshold and measuring specific HCO transitions by LIF. The PHOFEX spectra are subsequently normalized to the DFWM signals recorded simultaneously. The resulting fluorescence quantum yield spectra provide sensitive information on state‐specific propensities of the dissociation reaction. Copyright © 2005 John Wiley & Sons, Ltd.