bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, Characterization, and Self‐Assembly of Nitrogen‐Containing Heterocoronenetetracarboxylic Acid Diimide Analogues: Photocyclization of N‐Heterocycle‐Substituted Perylene Bisimides
Authors: Li Yongjun , Li Yuliang , Li Junbo , Li Cuihong , Liu Xiaofeng , Yuan Mingjian , Liu Huibiao , Wang Shu
Published: August 2006

Novel dibenzocoronenetetracarboxylic acid diimide analogues and naphthoperylenetetracarboxylic acid diimide analogues containing imidazole, 1,2,4‐triazole, and pyrazole rings embedded as functional constituents within the parent hydrocarbon backbone have been synthesized. The π‐rich and π‐poor heterocycles have different influences on the physical properties of the parent benzocoronenetetracarboxylic acid diimide and naphthoperylenetetracarboxylic acid diimide systems. The π‐rich 3 was able to self‐assemble into one‐dimensional nanostructures through strong π–π stacking, whereas the π‐poor 8 lacked the one‐dimensional self‐assembly capability, thus offering the potential to control the self‐assembly capability of the π‐conjugated perylene core by decoration with N‐heterocycles.
Cytologic diagnosis of pancreatic endocrine tumors by endoscopic ultrasound‐guided fine‐needle aspiration: A review
Authors: Chang Fuju , Chandra Ashish , Culora Giuseppe , Mahadeva Ula , Meenan John , Herbert Amanda
Published: August 2006

Precise localization and diagnosis of pancreatic endocrine tumors (PETs) is important, because pancreatic PETs have different clinical and biological behavior and treatment modalities than do exocrine pancreatic tumors. In contrast to the much more common exocrine adenocarcinomas, cytologic studies of PET are relatively rare and many cytopathologists lack experience with the cytomorphologic features of these tumors.

During the last 10 yr, endoscopic ultrasound (EUS)‐guided fine‐needle aspiration (FNA) has matured into an accurate, highly sensitive, and cost‐effective modality for the preoperative localization of pancreatic PETs. This has resulted in an increased number of PETs first sampled as cytology specimens. This manuscript focuses on the cytomorphologic features most suggestive of pancreatic PETs, differential diagnosis, and diagnostic pitfalls of PETs. The technical development of EUS‐guided FNA and the ancillary studies for pancreatic PETs are also reviewed.

The data summarized in this review indicate that EUS‐FNA is a valuable method in the recognition of pancreatic PETs and in most cases cytopathologists could reach a correct diagnosis of these tumors, including their hormone producing capability on aspirated cytologic material. Diagn. Cytopathol. 2006;34:649–658. © 2006 Wiley‐Liss, Inc.
Dutch solutions for liquid‐based cytology: Analysis of unsatisfactory slides and HPV testing of equivocal cytology
Authors: Boon Mathilde E. , Rijkaart Dorien C. , Ouwerkerk‐Noordam Elisabeth , Korporaal Hans
Published: August 2006

The liquid‐based techniques to obtain microscopy slides for cervical screening have replaced conventional smears almost completely in the USA, but not in all European countries. The decision making process to use liquid‐based cytology (LBC) for nationwide screening programs depends on the health system. In a pilot study of over 7,000 screenees, we analyzed the unsatisfactory LBC slides and tested the equivocal cytologies for HPV by using the LiPA test. For comparison over 48,000 conventional screening data were used. Compared to conventional smears, the LBC slides were highly cellular, the state of fixation was much better, and obscuring blood did not exist. The unsatisfactory rate showed an increase from 262/100,000 (conventional smears) to 357/100,000 (LBC slides) due to too thick, undiagnosable epithelial fragments on the LBC slides. HPV testing of the equivocal cytology leads to a better patient management and less unnecessary referrals. Diagn. Cytopathol. 2006;34:644–648. © 2006 Wiley‐Liss, Inc.
K‐Ras and microsatellite marker analysis of fine‐needle aspirates from intraductal papillary mucinous neoplasms of the pancreas
Authors: Schoedel Karen E. , Finkelstein Sydney D. , Ohori N. Paul
Published: August 2006

Preoperative diagnosis of pancreatic cystic lesions is difficult despite the combination of cytomorphology, radiographic imaging characteristics, and fluid tumor markers such as carcinoembryonic antigen. Intraductal papillary mucinous neoplasms (IPMNs) represent a subset of preinvasive pancreatic cystic neoplasms and are associated with accumulated genetic mutations, especially K‐ras and tumor suppressor genes such as p53. Application of molecular techniques to cyst fluid obtained by endoscopic ultrasound guided fine‐needle aspiration (EUSFNA) may contribute to preoperative assessment.

Sixteen patients with pancreatic cystic lesions had cyst fluid obtained by preoperative pancreatic EUSFNA or intraoperative aspiration. All patients subsequently underwent surgical resection of the pancreas and IPMN was documented in all (6 adenomas, 6 borderline tumors, and 4 carcinomas). DNA was extracted from the cyst fluids and mutational analysis for K‐ras point mutations and loss of heterozygosity (LOH) analysis using a preselected panel of genomic loci were performed. LOH was observed in 3 of 4 carcinomas as compared to 4 of 11 adenomas and borderline lesions (1 was QNS). LOH and K‐ras mutations were both acquired in 2 of 4 carcinomas and in 1 of 12 adenoma/borderline lesions.

Although the study is small, molecular analysis for LOH and K‐ras mutations is useful in the preoperative evaluation of cystic pancreatic lesions. Increasing degree of neoplasia appears to correlate with increased genetic abnormality using a panel of selected genomic markers. Diagn. Cytopathol. 2006;34:605–608. © 2006 Wiley–Liss, Inc.
Endometrial glandular and stromal breakdown, part 1: Cytomorphological appearance
Authors: Shimizu Keiko , Norimatsu Yoshiaki , Kobayashi Tadao K. , Ogura Seiko , Miyake Yasuyuki , Ohno Eiji , Sakurai Takaki , Moriya Takuya , Sakurai Masami
Published: August 2006

Endometrial carcinoma is the most common invasive neoplasm of the female reproductive tract. Early detection and accurate diagnosis of these lesions and its precursor by endometrial cytology is now accepted in Japan and regarded as an effective primary method of evaluating endometrial pathology (atypical hyperplasia or carcinoma). Careful cytomorphologic evaluation of the abnormal endometrial lesions has made possible an accurate and reproducible microscopic assessment. The current study was conducted to determine the significance of endometrial cytology on disordered endometrium associated with anovulation when compared with endometrial hyperplasia. From January 1998 through April 2004, 144 cases on which histopathological diagnoses were obtained by endometrial curettage after taken direct endometrial sample by Endocyte. The materials comprise 49 cases of normal proliferative endometrium, and 63 cases of endometrial hyperplasia without atypia were prepared as control cases. The cytomorphology was examined involving so‐called endometrial glandular and stromal breakdown (EGBD). EGBD cases evidenced significant numbers of stromal cells condensed and formed compact nests with hyperchromatic nuclei and little or no cytoplasm. They were often associated with fragmented clusters of endometrial glands with condensed cluster of stromal cells.

Both the fragmented cluster of endometrial glands and condensed cluster of stromal cells are a characteristic cytologic feature of EGBD endometrium on the cyto‐architectural diagnosis. The combination of these cellular patterns is highly specific to this abnormal pathological condition in EGBD endometrium. To improve the accuracy of the cytodiagnosis, it is important that the cytology of the EGBD endometrium should be diagnosed negative; as a result, we can achieve successful endometrial cytology with cyto‐architectural criteria for the endometrial pathology. Diagn. Cytopathol. 2006;34:609–613. © 2006 Wiley–Liss, Inc.
Commentary on ‘Interventions for promoting the initiation of breastfeeding’, with response from the review authors
Authors: Waters Elizabeth , Doyle Jodie
Published: August 2006

This is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Dyson L, McCormick F, Renfrew MJ. Interventions for promoting the initiation of breastfeeding. Cochrane Database of Systematic Reviews 2005, Issue 2. Art. No.: CD001688. DOI: 10.1002/14651858.CD001688.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying EBCH Summary and Characteristics and Key Findings Tables articles. Copyright © 2006 John Wiley & Sons, Ltd.
Summary of ‘Vaccines for preventing influenza in healthy children’
Authors: Milne Andrea
Published: August 2006

This is a summary of a Cochrane review, published in this issue of EBCH, first published as: Smith S, Demicheli V, Di Pietrantonj C, Harnden AR, Jefferson T, Matheson NJ, Rivetti A. Vaccines for preventing influenza in healthy children. Cochrane Database of Systematic Reviews 2006, Issue 1. Art. No.: CD004879. DOI: 10.1002/14651858.CD004879.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Expert Commentary and Characteristics and Key Findings Tables articles. Copyright © 2006 John Wiley & Sons, Ltd.
Characteristics and key findings for ‘Interventions for promoting the initiation of breastfeeding’
Authors: van Dalen Elvira , Offringa Martin , Kremer Leontien
Published: August 2006

These are the characteristics and key findings for a Cochrane review, published in this issue, first published as: Dyson L, McCormick F, Renfrew MJ. Interventions for promoting the initiation of breastfeeding. Cochrane Database of Systematic Reviews 2005, Issue 2. Art. No.: CD001688. DOI: 10.1002/14651858.CD001688.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying EBCH Summary and Expert Commentary articles. Copyright © 2006 John Wiley & Sons, Ltd.
Design and evaluation of the cache coherent multistage interconnection network with temporary directory
Authors: Midorikawa Takashi , Sumiyoshi Masato , Tanabe Yasuki , Amano Hideharu
Published: August 2006

Although cache control mechanisms for use in multiprocessors that use a multistage interconnection network (MIN) as the interconnecting network have been proposed in which a directory or the cache itself is built into the switches in the MIN, the structure of the switches in these methods have been complex and there therefore remains room for improvement. Our research group has therefore proposed a MIN with directory cache switch (MINDIC) that implements cache control by only building small‐ capacity directory caches into the switches. This paper reports on the results of evaluating MINDIC using a clock level simulator. The results reveal that MINDIC is able to achieve a level of cache control efficiency that is equal to that of a full map directory management scheme by setting the number of entries in the MINDIC directory caches to approximately 2048 entries. The results also show that the amount of memory required for the directory can be greatly reduced by MINDIC. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 89(9): 11–23, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20301
Impaired regulatory T cell function in germ‐free mice
Authors: Östman Sofia , Rask Carola , Wold Agnes E. , Hultkrantz Susanne , Telemo Esbjörn
Published: August 2006

Regulatory T cells (Treg) are crucial for the maintenance of tolerance to auto‐antigens and harmless exogenous antigens. Here, we studied the role of the commensal microbiota for the development and function of Treg. CD4+CD25+ T cells were obtained from peripheral lymph nodes (PLN) and mesenteric lymph nodes (MLN) of germ‐free (GF) and conventional (conv) NMRI mice and tested for phenotype and functional suppressive capacity. CD4+CD25+ T cells from GF mice showed a lower relative gene expression of fork head box p3 gene (Foxp3) and were not as potent suppressors in vitro as CD4+CD25+ T cells from conv animals. Intracellular staining for Foxp3 and CTLA‐4 revealed proportional and regional differences in putative Treg subsets between conv and GF mice. Fewer of the CD4+CD25+ T cells in GF MLN expressed Foxp3 and CTLA‐4, while the expression of these markers was similar amongst the CD4+CD25+ T cells in PLN of conv and GF mice. The largest difference between conv and GF Treg was observed in the liver draining celiac lymph node, where GF mice had fewer putative Treg as compared to conv mice. We propose that the presence of a microbial flora favors the development of a fully functional Treg population.
A Cationic Order‐Disorder Phase Transition in KPb2Cl5
Authors: Velázquez Matias , Ferrier Alban , Pérez Olivier , Péchev Stanislas , Gravereau Pierre , Chaminade Jean‐Pierre , Moncorgé Richard
Published: August 2006

The phase transition occurring at Tt = 528 K in the natural mineral and synthetic laser host compound KPb2Cl5 has been characterized by means of both single‐crystal X‐ray diffraction (XRD) as a function of temperature and differential scanning calorimetry (DSC). The K+ and Pb2+(2) cations order on passing from the high‐temperature orthorhombic phase (space group Pmcn; a = 8.951, b = 8.015, c = 12.683 Å, Z = 4 at 623 K) to the low‐temperature monoclinic one (space group P21/c; a = 8.849, b = 7.918, c = 12.472 Å, β = 90.11°, Z = 4, at room temperature), leading to a group‐subgroup first‐order phase transition displaying moderately fast kinetics and low entropy production upon thermal cycling around Tt. The positional entropy calculated from our crystal structure models corresponds to the transition entropy measured by DSC within the experimental error, and amounts to about 0.34 R. The driving force for the phase transition, A ≤ 22 J mol–1, remains negligible with respect to both the thermal energy at Tt (RTt ≈ 4.4 kJ mol–1) and the transition latent heat (ΔH ≈ 790 J mol–1), thereby suggesting that this phase transition is a close‐to‐equilibrium process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
An Asymmetric, Chemo‐Enzymatic Synthesis of O‐Acetylcyanohydrins
Authors: Belokon Yuri N. , Blacker A. John , Clutterbuck Lisa A. , Hogg David , North Michael , Reeve Christopher
Published: August 2006

A one‐pot chemo‐enzymatic synthesis of highly enantiomerically enriched O‐acetylcyanohydrins has been developed. The bimetallic (salen)titanium complex 1 is used to convert aldehydes into nonracemic (R)‐O‐acetylcyanohydrins with 61 to 93 % enantiomeric excess. A lipase enzyme is then used to hydrolyse the unwanted (S) enantiomer of the product, leaving (R)‐O‐acetylcyanohydrins with 80 to >99 % enantiomeric excess and in 75 to 96 % overall yield. Of ten lipase enzymes investigated, Candida antarctica lipase‐B (CAL‐B) has been shown to be the most suitable and the conditions for its use have been optimised. Although no single solvent has been found in which both catalyst 1 and CAL‐B gave high reaction rates and enantioselectivities, two procedures to allow their sequential use without purification of the O‐acetylcyanohydrin produced by catalyst 1 have been developed. In the first of these, the reaction with catalyst 1 is carried out in dichloromethane which is then removed and replaced with methyl tert‐butyl ether prior to addition of the enzyme. In the second procedure, the first reaction is carried out in concentrated dichloromethane solution, and this is then just diluted with methyl tert‐butyl ether prior to addition of the lipase. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Electrocatalytic Reduction of Chromium(VI) by Thionin: Electrochemical Properties and Mechanistic Study
Authors: Salimi Abdollah , Amini Nader , Danyali Habibollah , Hallaj Rahman
Published: August 2006

The electrochemical properties of aqueous thionin (an electroactive water soluble dye) of pH 1–12 were investigated by cyclic voltammetry at a boron doped diamond(BDD) electrode. A well defined reversible redox couple was observed in acidic, neutral and alkaline solutions. The standard potential and kinetic parameters for thionin were obtained by fitting experimental cyclic voltammograms to those generated by the DigiSim program. The electrogenerated reduced form of thionin has been used as an efficient organic catalyst for the reduction of Cr(VI) at a BDD electrode immersed in aqueous media. The cyclic voltammetry measurements indicate that an electrocatalytic process occurs, where electrochemically generated thionin reduced species (Leucothionin) is oxidized by Cr(VI) back to the parent thionin species via a EC' reaction mechanism. The determination of catalytic rate constant (Kcat) was accomplished again by fitting experimental cyclic voltammograms with simulated ones.
UV‐Visible and Electrochemical Monitoring of Carbon Monoxide Release by Donor Complexes to Myoglobin Solutions and to Electrodes Modified with Films Containing Hemin
Authors: Obirai Joseph C. , Hamadi Sarah , Ithurbide Aurélie , Wartelle Corinne , Nyokong Tebello , Zagal José , Top Siden , Bedioui Fethi
Published: August 2006

This study reports on the evaluation of the CO donating behavior of tricarbonyl dichloro ruthenium(II) dimer ([Ru(CO)3Cl2]2) and 1,3‐dimethoxyphenyl tricarbonyl chromium (C6H3(MeO)2Cr(CO)3) complex by UV‐visible technique and electrochemical technique. The CO release was monitored by following the modifications of the UV‐visible features of MbFe(II) in phosphate buffer solution and the redox features of reduced Hemin, HmFe(II), confined at the surface of a vitreous carbon electrode. In the latter case, the interaction between the hemin‐modified electrode and the released CO was seen through the observation of an increase of the reduction current related to the FeIII/FeII redox process of the immobilized porphyrin. While the ruthenium‐based complex, ([Ru(CO)3Cl2]2), depended on the presence of Fe(II) species to release CO, it was found that the chromium‐based complex released spontaneously CO. This was facilitated by illuminating and/or simple stirring of the solution containing the complex.
Gold Nanoparticles Doped Three‐Dimensional Sol‐gel Matrix for Amperometric Human Chorionic Gonadotrophin Immunosensor
Authors: Chen Jin , Yan Feng , Tan Fang , Ju Huangxian
Published: August 2006

A novel electrochemical immunosensor for human chorionic gonadotrophin (hCG) was proposed by immobilization of hCG in gold nanoparticles doped three‐dimensional (3D) sol‐gel matrix and an interfacial competitive immunoreaction. The 3D organized composite structure was prepared by assemble of gold nanoparticles into a hydrolyzed (3‐mercaptopropyl)‐trimethoxysilane sol‐gel matrix, which showed good biocompatibility. After the interfacial competitive immunoreaction the formed HRP‐labeled immunoconjugate showed good enzymatic activity for the oxidation of o‐phenylenediamine by H2O2. With a competitive format, a method comprising of o‐phenylenediamine‐H2O2‐immobilized HRP labeled hCG immunoconjugate system for immunoassay of hCG from 5.0 to 30.0 mIU mL−1 was developed. The immunosensor showed good precision, high sensitivity, acceptable stability and reproducibility and could be used for detection of hCG in human serum with the consistent results in comparison with those obtained by a commercial analyzer.
Effects of Electroplating Variables on the Voltammetric Properties of Bismuth Deposits Plated Potentiostatically
Authors: Królicka Agnieszka , Bobrowski Andrzej , Kowal Andrzej
Published: August 2006

An attempt is made to describe the electrochemical properties of bismuth films, plated in‐situ on glassy carbon in acetic buffer, over a broad range of deposition potentials. It is shown that accumulation during anodic stripping voltammetric determination of lead and zinc at the bismuth film electrode depends to a large extent on the electrolyte composition and the plating parameters. The influence of the plating potential on Pb deposition is moderate, but it could not be disregarded during Zn quantification. The sources of electrode poisoning effects are discussed in detail. Voltammetric studies are complemented by AFM microscopic observations.
Amperometric Detection of Sulfide: An Electrocatalytic Reaction with Ferrocene Carboxylate
Authors: Lawrence Nathan S.
Published: August 2006

The electrocatalytic oxidation of sulfide and sulfhydryl thiol species by ferrocene carboxylate at both glassy carbon and boron doped diamond electrodes is examined. The enhancement in the oxidative current recorded in the presence of sulfide, allowed linear ranges up to 1 mM for sulfide detection to be achieved. In the absence of the mediator, no defined oxidation wave was observed for the direct oxidation of sulfide. Furthermore, the use of hydrodynamic voltammetry produced a limit of detection of 2 μM. The procedure was applied to the recovery of a sulfide spike in river water, with a recovery of 104% obtained.
A PVC/TTF‐TCNQ Composite Electrode for Use as a Detector in Flow Injection Analysis
Authors: Cano Manuel , Palenzuela Beatriz , Rodríguez‐Amaro Rafael
Published: August 2006

A new polyvinyl chloride (PVC)/tetrathiafulvalene‐tetracyanoquinodimethane (TTF‐TCNQ) composite electrode was prepared and tested for electroanalytical performance. Different PVC/TTF‐TCNQ–graphite proportions were used in order to obtain the best possible detector for accommodation in a wall‐jet electrochemical cell of use in flow injection analysis. A PVC/TTF‐TCNQ w/w ratio of 1/10 provided the best results in terms of sensitivity, coefficients of variation and mechanical resistance. The voltammetric and flow‐injection amperometric detection responses of the electrode to ascorbic acid (AA) were measured and compared with those of a PVC–graphite electrode. The resulting electrode provided good electrode kinetics with a low background current and a relatively reproducible signal. In addition, the electrode can be readily prepared and its surface readily renewed.
Rapid Pretreatment of a Solid Silver Electrode for Routine Analytical Practice
Authors: Baś Bogusław , Jakubowska Małgorzata , Kowalski Zygmunt
Published: August 2006

A very fast electrochemical method for renovation of solid electrodes and storage of the electrodes in a ready for use state, as well as necessary original hardware, is presented in this work. The device has the shape of a cylindrical container with a volume of about 3–5 mL filled with an electrolyte solution in which auxiliary and reference electrodes are placed. It may be fastened in a typical electrochemical cell. The method relies on suitable electrode polarization in the device. During the renovation process, the electrode is inside the device and immediately after the activation, it is moved into the tested solution where the measurement is realized.
Influence of experimental removal of large woody debris on spatial patterns of three‐dimensional flow in a meander bend
Authors: Daniels Melinda D. , Rhoads Bruce L.
Published: August 2006

This study reports the results of a large woody debris (LWD) removal experiment in a meander bend along a low‐energy stream in the Midwestern United States. The LWD obstacle was located in the center of the channel at the bend exit and consisted of a mature tree with an intact soil‐covered root wad and a large accumulation of logs, branches and pieces of lumber on top of and adjacent to the main tree. The results indicate that the LWD obstruction influenced 3D flow structure in this bend at all flow stages. The main effect of LWD is to dramatically decelerate flow throughout the majority of the bend, while locally accelerating flow where it passes through the narrow chute at the downstream end of the LWD obstruction. Results from the LWD removal experiment indicate that patterns of three‐dimensional flow structure in meander bends are sensitive to complete removal of LWD. After the removal of LWD from the bend, both downstream and secondary velocities increased and, though still weak, secondary flow intensified. Large, relatively stable, obstructions that span a significant portion of the channel may act as natural dams, effectively ponding water upstream of the LWD, thereby producing substantial convective deceleration of the flow. This research is the first to document three‐dimensional flow structure before and after a controlled removal of LWD from a meander bend. Studies of the type reported here represent a first step toward determining the ensemble of process interactions between LWD and bend dynamics. Copyright © 2006 John Wiley & Sons, Ltd.
A Sulfophenylated Polysulfone as the DMFC Electrolyte Membrane – an Evaluation of Methanol Permeability and Cell Performance
Authors: Vernersson T. , Lafitte B. , Lindbergh G. , Jannasch P.
Published: August 2006

A sulfophenylated polysulfone (PSU‐sph), carrying 0.8 sulfonic acid units per repeating unit of the polymer, is evaluated as a membrane electrolyte for DMFC applications. The liquid uptake, methanol transport characteristics, electrolyte conductivity, and fuel cell performance are investigated. The methanol transport and DMFC performance results are compared to those of Nafion® 117. The PSU‐sph membrane investigated shows superior qualities with regard to methanol crossover, with a methanol permeability of approximately 25% compared to that of Nafion®. The conductivity was measured to be 15% compared to that of Nafion®. However, this could not fully account for the internal resistance of the cell, implying that the contact resistance between the electrodes and electrolyte is higher when PSU‐sph is used, probably because the electrodes are developed for use with Nafion® membranes. The stability of the PSU‐sph membrane seems promising, with very low degradation observed over a period of 72 hours. It was concluded that although the mass transport properties of the PSU‐sph membrane sample investigated were superior, it could not match the performance of Nafion® 117 in a DMFC application. However, a higher degree of sulfonation may have a significant positive effect on cell performance. The results also showed that a fully intergrated MEA is needed to fully assess new menbrane materials.
Start Up and Freezing Processes in PEM Fuel Cells
Authors: Oszcipok M. , Hakenjos A. , Riemann D. , Hebling C.
Published: August 2006

The isothermal operation of single PEM fuel cells below 0 °C is investigated by potentiostatic experiments and analyzed by physical modeling. Current decay is observed during potentiostatic operation, which is caused by the freezing of product water in the porous cathode layers.

This paper describes the implementation of the ohmic losses and changes of the active cathode area as a function of the charge transfer density in a physical PEM fuel cell model. The model is comprised of a set of differential equations accounting for the electrochemical reaction and diffusion processes in the cathode of the fuel cell.

The model describes the time‐resolved current decay during freezing. Thus a better understanding of freezing processes at sub‐zero conditions in PEM fuel cells is gained and mechanisms proposed from earlier experimental data and statistical based interpretations are confirmed. Furthermore, the transient water uptake behavior of the membrane is studied in situ at different temperatures.
The rise of ginkgoalean plants in the early Mesozoic: a data analysis
Authors: Zhiyan Zhou , Xiangwu Wu
Published: August 2006

In the present article, ginkgoalean fossil records are analysed and the data are incorporated into a sketched, ‘epoch‐by‐epoch’ framework (e.g. late Triassic, early Jurassic), based on the latest biostratigraphical evidence and the recent progress made mainly on the reproductive organs. The analyses revealed that a steep increase in diversity occurred from the middle Triassic onwards and during the late Triassic ginkgoaleans were at the zenith of diversity. In the late Triassic, almost all known ginkgoalean families simultaneously occurred. The diversity of vegetative organs increased rapidly, forming a high peak in the number of genera (8 in China and 12 in the world). In the late Triassic, in marked contrast to the absence of any record in the middle Triassic, there occurred the most diversified ginkgoalean reproductive structures so far known in the geological record. The emergence of a large number of new genera also supports an early Mesozoic, notably a late Triassic radiation of ginkgoaleans. In China, Ginkgo was recorded firstly in the late Triassic, and the commonest morphogenera Ginkgoites, Baiera and Sphenobaiera drastically increased in specific (or morphotypic) diversity from the late Triassic onwards accompanied by very high origination rates of 88.8, 100 and 91.7%, respectively. The major morphological innovations of vegetative organs accomplished in the middle to late Triassic are the appearance of dwarf shoots and the differentiation of leaves into lamina and petiole. Since then, the reduction of pedicels and number of ovules, and the increase in size of ovules became dominant. Further morphological innovations and diversification of ginkgoalean ovule organs include the fused or adnate ovule/bract, and the collared or winged ovules. In China, ginkgoaleans also started expanding rapidly in geographical distribution from the middle Triassic to the late Triassic. The fossil localities of Ginkgo increased from zero to three, Ginkgoites from one to 12, Baiera zero to 27 and Sphenobaiera three to 20 counties.

The replacement of the warm‐hot, nearly uniform climate with long growing season in the late Palaeozoic by the seasonal climate in the early Mesozoic of Eurasia was probably the main cause of a marked reduction of both vegetative and reproductive organs of ginkgoaleans. The latest Triassic plate movement and sea‐level change that resulted in considerable habitat heterogeneity might also facilitate an increase in taxon and morphology diversity of this present‐day relictual plant group. Copyright © 2006 John Wiley & Sons, Ltd.
Analysis of immunoglobulin heavy and light chain variable genes in post‐transplant lymphoproliferative disorders
Authors: Capello Daniela , Cerri Michaela , Muti Giuliana , Lucioni Marco , Oreste Pierluigi , Gloghini Annunziata , Berra Eva , Deambrogi Clara , Franceschetti Silvia , Rossi Davide , Alabiso Oscar , Morra Enrica , Rambaldi Alessandro , Carbone Antonino , Paulli Marco , Gaidano Gianluca
Published: August 2006

Post‐transplant lymphoproliferative disorders (PTLD) derive from antigen‐experienced B‐cells and represent a major complication of solid organ transplantation. We characterized usage, mutation frequency and mutation pattern of immunoglobulin variable (IGV) gene rearrangements in 50 PTLD (polymorphic PTLD, n=10; diffuse large B‐cell lymphoma, n=35; and Burkitt/Burkitt‐like lymphoma, n=5). Among PTLD yielding clonal IGV amplimers, a functional IGV heavy chain (IGHV) rearrangement was found in 40/50 (80.0%) cases, whereas a potentially functional IGV light chain rearrangement was identified in 36/46 (78.3%) PTLD. By combining IGHV and IGV light chain rearrangements, 10/50 (20.0%) PTLD carried crippling mutations, precluding expression of a functional B‐cell receptor (BCR). Immunohistochemistry showed detectable expression of IG light chains in only 18/43 (41.9%) PTLD. Failure to detect a functional IGV rearrangement associated with lack of IGV expression. Our data suggest that a large fraction of PTLD arise from germinal centre (GC)‐experienced B‐cells that display impaired BCR. Since a functional BCR is required for normal B‐cell survival during GC transit, PTLD development may implicate rescue from apoptosis and expansion of B‐cells that have failed the GC reaction. The high frequency of IGV loci inactivation appears to be a peculiar feature of PTLD among immunodeficiency‐associated lymphoproliferations. Copyright © 2006 John Wiley & Sons, Ltd.
Quantum mechanical calculation of the effects of stiff and rigid constraints in the conformational equilibrium of the alanine dipeptide
Authors: Echenique Pablo , Calvo Iván , Alonso J. L.
Published: August 2006

If constraints are imposed on a macromolecule, two inequivalent classical models may be used: the stiff and the rigid one. This work studies the effects of such constraints on the conformational equilibrium distribution (CED) of the model dipeptide HCO‐L‐Ala‐NH2without any simplifying assumption. We use ab initio quantum mechanics calculations including electron correlation at the MP2 level to describe the system, and we measure the conformational dependence of all the correcting terms to the naive CED based in the potential energy surface that appear when the constraints are considered. These terms are related to mass‐metric tensors determinants and also occur in the Fixman's compensating potential. We show that some of the corrections are non‐negligible if one is interested in the whole Ramachandran space. On the other hand, if only the energetically lower region, containing the principal secondary structure elements, is assumed to be relevant, then, all correcting terms may be neglected up to peptides of considerable length. This is the first time, as far as we know, that the analysis of the conformational dependence of these correcting terms is performed in a relevant biomolecule with a realistic potential energy function. © 2006 Wiley Periodicals, Inc. J Comput Chem, 2006
Flooding in GROMACS: Accelerated barrier crossings in molecular dynamics
Authors: Lange Oliver F. , Schäfer Lars V. , Grubmüller Helmut
Published: August 2006

The major bottleneck of today's atomistic molecular dynamics (MD) simulations is that because of the enormous computational effort involved, only processes at nanoseconds to microseconds time scales or faster can be studied directly. Unfortunately, apart from a few exceptions, relevant processes, such as chemical reactions or many large scale conformational transitions in proteins, occur at slower time scales and therefore are currently far out of reach for conventional MD. The flooding technique addresses this problem by inclusion of a flooding potential into the force field. This flooding potential locally destabilizes the educt state and thereby significantly accelerates the escape from the initial energy well without affecting the reaction pathway. Here, we summarize the theory and method for the computational chemistry community and detail the implementation within the official version 3.3 of the freely available MD program package GROMACS. Two examples shall demonstrate the application of flooding to accelerate conformational transitions and chemical reactions. The second example was carried out within a QM/MM framework. © 2006 Wiley Periodicals, Inc. J Comput Chem, 2006
Second derivatives in generalized Born theory
Authors: Brown Russell A. , Case David A.
Published: August 2006

Generalized Born solvation models offer a popular method of including electrostatic aspects of solvation free energies within an analytical model that depends only upon atomic coordinates, charges, and dielectric radii. Here, we describe how second derivatives with respect to Cartesian coordinates can be computed in an efficient manner that can be distributed over multiple processors. This approach makes possible a variety of new methods of analysis for these implicit solvation models. We illustrate three of these methods here: the use of Newton‐Raphson optimization to obtain precise minima in solution; normal mode analysis to compute solvation effects on the mechanical properties of DNA; and the calculation of configurational entropies in the MM/GBSA model. An implementation of these ideas, using the Amber generalized Born model, is available in the nucleic acid builder (NAB) code, and we present examples for proteins with up to 45,000 atoms. The code has been implemented for parallel computers using both the OpenMP and MPI environments, and good parallel scaling is seen with as many as 144 OpenMP processing threads or MPI processing tasks. © 2006 Wiley Periodicals, Inc. J Comput Chem 2006
Lipid assessment and treatment patterns in hospitalized TIA and ischemic stroke patients
Authors: Ovbiagele Bruce , Hills Nancy K. , Saver Jeffrey L. , Johnston S. Claiborne ,   For the CASPR Investigators
Published: August 2006

BACKGROUND

Identification of dyslipidemia and treatment with lipid‐lowering agents are established targets for quality performance during hospitalization for ischemic stroke and transient ischemic attack (TIA). We aimed to study the frequency and predictors of lipid assessment and discharge utilization of lipid‐lowering therapies among patients hospitalized for stroke and TIA.

METHODS

Demographics, clinical findings, and laboratory data were documented as part of the California Acute Stroke Prototype Registry (CASPR). Frequency of low‐density lipoprotein cholesterol (LDL‐C) testing and the frequency and appropriate use of lipid‐lowering treatment according to national cholesterol guidelines were determined. Multivariate models were generated to determine the contribution of clinical variables to LDL testing and prescription of lipid‐lowering medications at discharge.

RESULTS

Data were collected on 764 consecutive patients with ischemic stroke or TIA treated at 11 hospitals over a 2‐year period. LDL‐C measurements were performed in only 50.1% during hospitalization. Measurement of LDL‐C was most strongly and independently associated with diagnosis of ischemic stroke (vs. TIA, P = .02) and history of dyslipidemia (P = .05). Overall, 48.4% of the CASPR cohort received lipid‐lowering medications at discharge. Independent predictors for being prescribed lipid‐lowering agents at discharge were diagnosis of ischemic stroke (P = .0009), LDL‐C testing (P = .0002), high risk of future coronary events according to national guidelines (P = .02), and history of dyslipidemia (P< .0001). Only 59% of patients at high risk for future coronary events were discharged on a lipid‐lowering medication.

CONCLUSIONS

Serum cholesterol testing and treatment are underutilized during hospitalization for ischemic stroke or TIA. Journal of Hospital Medicine 2006;1:214–220. © 2006 Society of Hospital Medicine.
Fatty acid composition, including isomeric profile of conjugated linoleic acid, and cholesterol in Mertolenga‐PDO beef
Authors: Alfaia Cristina MM , Quaresma Mário AG , Castro Matilde LF , Martins Susana IV , Portugal Ana PV , Fontes Carlos MGA , Bessa Rui JB , Prates José AM
Published: August 2006

This paper describes the fatty acid composition, including the isomeric distribution of conjugated linoleic acid (CLA), total lipids and cholesterol in longissimus dorsi (LD) and semitendinosus (ST) muscles of Mertolenga beef from young bulls reared according to Protected Designation of Origin (PDO) specifications. Mertolenga purebred young bulls (n = 30) were raised in a semi‐extensive production system, including a finishing period on concentrate feeds for the last 5 or 3 months (October and June samplings, respectively). Mertolenga‐PDO beef showed seasonal changes in the levels of some fatty acids (including the predominant 18:2n‐6), sums of trans fatty acids and n‐3 polyunsaturated fatty acids, some CLA isomers (t11,t13, t11,c13 and t10,c12), sums of geometric groups of CLA isomers and total cholesterol. In addition, significant differences were obtained between LD and ST muscles for most of the analysed parameters. From a nutritional perspective, beef‐PDO from June seems to be more healthful than that from October as a consequence of its lower n‐6/n‐3 ratio. Moreover, the results suggest that the polyunsaturated fatty acid/saturated fatty acid ratio in the ST muscle is consistently above the recommended guideline for human diets, although the values were below that guideline for the LD muscle. Taken together, the data indicate that, although the finishing period of Mertolengo young bulls on concentrate attenuates most of the beneficial grass effects on meat fat throughout the year, beef‐PDO from late spring is of greater nutritional value than that from early autumn. Copyright © 2006 Society of Chemical Industry
Photobleaching, light‐induced discolouration in red peppers
Authors: Jung Ji Won , Lee Seung Koo
Published: August 2006

Red peppers dried in sunlight experience surface bleaching, centred near the calyx, on the face exposed to the light. In this study, bleaching mechanisms were studied under simulated irradiation conditions by placing pericarp discs in 2‐(N‐morpholino) ethane sulfonic acid (MES) and sucrose solution. The moisture content near the calyx of the pepper decreased more slowly than that on the apex side. In addition, pericarp discs incubated without MES/sucrose solution retained more carotenoids than those incubated with solution after 27 h of light treatment. Carotenoids in pericarp discs exposed to the light decreased rapidly over the incubation time, whereas in the dark they decreased slowly and remained higher in content. Changes in malondialdehyde (MDA) level and electrolyte leakage were not observed for pericarp incubation in the dark. A sharp increase in the level of MDA and a change in electrolyte leakage from discs exposed to the light occurred when carotenoids were exhausted. Carotenoid degradation was markedly suppressed by the addition of ascorbic acid. These results demonstrate that carotenoids in red pepper pericarp played a role in protecting cells and were subsequently degraded under intense light conditions. Copyright © 2006 Society of Chemical Industry
Stimulated Raman scattering and cascaded nonlinear laser
(χ(3) ↔ χ(2)) effects in tetragonal
non-centrosymmetric Li2B4O7 single crystals
Authors: Kaminskii A A , Bohatý L , Becker P , Liebertz J , Eichler H J , Rhee H
Published: August 2006

Multiple stimulated Raman scattering (SRS) and cascaded
nonlinear χ(3) ↔ χ(2)
generation in tetragonal non-centrosymmetric Li2B4O7
crystal were observed under picosecond
Nd3+:Y3Al5O12 laser excitation. All registered
Stokes and anti-Stokes lasing components in the visible and
near-IR were identified and attributed to the SRS-promoting
vibration modes of the studied crystal. We classify the
Li2B4O7 crystals as a promising media for up- and
down-Raman laser-frequency converters. In the work a brief review
of nonlinear-laser properties of SRS-active borate crystals is
given.
Opérateurs d'extension linéaires explicites dans des intersections de classes ultradifférentiables
Authors: Beaugendre Pascal
Published: August 2006

B. S. Mityagin a montré que les polynômes de Tchebyshev forment une base de Schauder de l'espace des fonctions de classe C ∞ sur l'intervalle [–1,1]. Il en déduit un opérateur linéaire continu d'extension explicite. Ces résultats ont été étendus, par A. Goncharov, à des compacts ne satisfaisant pas la propriété de Markov. A contrario, M. Tidten a donné des exemples de compacts pour lesquels il n'y a pas d'opérateur linéaire continu d'extension. Dans cet article, on généralise ces travaux à des classes de fonctions ultradifférentiables construites sur le modèle de l'intersection des classes de Gevrey non quasi‐analytiques. On obtient notamment un théorème d'extension linéaire dans des classes de Beurling assez grandes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Weakly Nehari functions, hyperbolic convexity and John disks
Authors: Chuaqui Martin , Herreros Pilar
Published: August 2006

In this paper, we extend some recent results by K. Hag and P. Hag regarding a generalized Nehari class. In particular, we give a description of this new class in terms of the hyperbolic metric, and characterize the unbounded functions in an analogue of a theorem of Gehring and Pommerenke. We also derive several sharp distortion theorems and estimates on the pre‐Schwarzian that are used to study John disks. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A connection between Schur multiplication and Fourier interpolation. II
Authors: McCloud N. , McEachin R.
Published: August 2006

Given m × n matrices A = [ajk ] and B = [bjk ], their Schur product is the m × n matrix A ○ B = [ajkbjk ]. For any matrix T, define ‖T‖ S = maxX ≠O ‖T ○ X ‖/‖X ‖ (where ‖·‖ denotes the usual matrix norm). For any complex (2n – 1)‐tuple μ = (μ –n +1, μ –n +2, …, μ n –1), let Tμ be the Hankel matrix [μ –n +j +k –1]j,k and define

𝔅μ = {f ∈ L 1[–π, π] : f̂ (2j ) = μj for –n + 1 ≤ j ≤ n – 1} .

It is known that ‖Tμ‖ S ≤ inf ‖f ‖1. When equality holds, we say Tμ is distinguished. Suppose now that μ j ∈ ℝ for all j and hence that Tμ is hermitian. Then there is a real n × n hermitian unitary X and a real unit vector y such that 〈(Tμ ○ X )y, y 〉 = ‖Tμ ‖S . We call such a pair a norming pair for Tμ . In this paper, we study norming pairs for real Hankel matrices. Specifically, we characterize the pairs that norm some distinguished Schur multiplier Tμ . We do this by giving necessary and suf.cient conditions for (X, y ) to be a norming pair in the n ‐dimensional case. We then consider the 2‐ and 3‐dimensional cases and obtain further results. These include a new and simpler proof that all real 2 × 2 Hankel matrices are distinguished, and the identi.cation of new classes of 3 × 3 distinguished matrices. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of set‐valued conditional expectation
Authors: Zohry M.
Published: August 2006

For an essentially bounded closed‐convex‐nonempty set‐valued random variable, it is shown that the conditional expectation is characterized by its integrals over the sets of the associated σ ‐field. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical analysis of dissolution processes in cementitious materials using discontinuous and continuous Galerkin time integration schemes
Authors: Kuhl Detlef , Meschke Günther
Published: August 2006

The present paper is concerned with the numerical integration of non‐linear reaction–diffusion problems by means of discontinuous and continuous Galerkin methods. The first‐order semidiscrete initial value problem of calcium leaching of cementitious materials, based on a phenomenological dissolution model, an electrolyte diffusion model and the spatial p‐finite element discretization, is used as a highly non‐linear model problem. A p‐finite element method is used for the spatial discretization. In the context of discontinuous Galerkin methods the semidiscrete mass balance and the continuity of the primary variables are weakly formulated within time steps and between time steps, respectively. Continuous Galerkin methods are obtained by the strong enforcement of the continuity condition as special cases. The introduction of a natural time co‐ordinate allows for the application of standard higher order temporal shape functions of the p‐Lagrange type and the well‐known Gauss–Legendre quadrature of associated time integrals. It is shown, that arbitrary order accurate integration schemes can be developed within the framework of the proposed temporal p‐Galerkin methods. Selected benchmark analyses of calcium dissolution demonstrate the robustness of these methods with respect to pronounced changes of the reaction term and non‐smooth changes of Dirichlet boundary conditions. Copyright © 2006 John Wiley & Sons, Ltd.
Evaluation of supersingular integrals: second‐order boundary derivatives
Authors: Moore M. N. J. , Gray L. J. , Kaplan T.
Published: August 2006

The boundary integral representation of second‐order derivatives of the primary function involves second‐order (hypersingular) and third‐order (supersingular) derivatives of the Green's function. By defining these highly singular integrals as a difference of boundary limits, interior minus exterior, the limiting values are shown to exist. With a Galerkin formulation, coincident and edge‐adjacent supersingular integrals are separately divergent, but the sum is finite, while the individual hypersingular integrals are finite. Moreover, the cancellation of the supersingular divergent terms only requires a continuous interpolation of the surface potential, and there is no continuity requirement on the surface flux. The algorithm is efficient, the non‐singular integrals vanish and the singular integrals are computed entirely analytically, and accurate values are obtained for smooth surfaces. However, it is shown that a (continuous) linear interpolation is not appropriate for evaluation at boundary corners. Published in 2006 by John Wiley & Sons, Ltd.