bluuebunny/crossref_metadata_2025 huggingface dataset:
Stereocomplementary Desymmetrizations of Divinylcarbinols by Zirconium(IV)‐ vs. Titanium(IV)‐Mediated Asymmetric Epoxidations
Authors: Kramer Rainer , Berkenbusch Thilo , Brückner Reinhard
Published: April 2008

Substituted Cs‐symmetric penta‐1,4‐dien‐3‐ols (“divinylcarbinols”) containing cis‐ or trans‐di‐substituted CC bonds were desymmetrized by asymmetric monoepoxidations. Sharpless conditions gave anti‐configured monoepoxides. For cis,cis‐divinylcarbinols this was unprecedented. Oxidation with tert‐butyl hydroperoxide (t‐BuOOH) in the presence of zirconium tetraisopropoxide [Zr(O‐i‐Pr)4] and a dialkyl tartrate led to the corresponding syn‐configured monoepoxides. Under the reaction conditions the ee of monoepoxide syn‐12 increased with time from 75 to 99% ee. The reason is the preferential overoxidation of its minor enantiomer. The ease of preparation and multitude of functional groups make epoxides 12–14 worthwhile building blocks for the synthesis of non‐racemic structures.
Congenital disseminated neurofibromatosis type 1: A clinical and molecular case report
Authors: Stewart H. , Bowker C. , Edees S. , Smalley S. , Crocker M. , Mechan D. , Forrester N. , Spurlock G. , Upadhyaya M.
Published: April 2008

Neurofibromatosis type 1 (NF1) is an autosomal dominant condition with a birth incidence of 1/3,500. Around 50% of cases are due to new mutations. The NF1 gene maps to 17q11.2 and encodes neurofibromin. NF1 is a “classical” tumor suppressor gene. Congenital disseminated NF1 is rare with just two cases previously reported. We present a deceased baby with congenital disseminated NF1 in whom we performed molecular studies. A germline mutation (R461X) in exon 10a of the NF1 gene was found. A 2 bp deletion (3508delCA) in codon 1170 of exon 21 was identified in DNA derived from some tumor tissue. Loss of heterozygosity in NF1 and TP53 was observed in other tumor samples. No microsatellite instability was observed in the tumor samples. This is the first report of molecular analysis of the NF1 locus in a patient with disseminated congenital neurofibromatosis. This case had a de novo germline mutation in NF1 and three documented somatic mutations in the NF1 and TP53 genes in tumor specimens. © 2008 Wiley‐Liss, Inc.
Solvent resistance and mechanical properties in thermoplastic elastomer blends prepared by dynamic vulcanization
Authors: Van Dyke J. D. (Jack) , Gnatowski Marek , Burczyk Andrew
Published: April 2008

Dynamic vulcanization was used to prepare thermoplastic elastomer blends of nylon (polyamide), polypropylene (PP) and polybutylene terephthalate thermoplastics with chlorobutyl (CIIR) and nitrile (NBR) rubbers. Mechanical properties of the blends were correlated against composition. Although hardness and tensile strength increase with increasing thermoplastic content for all blends, elongation at break values initially decrease and then increase in the range of 20–40% thermoplastic. For various blend compositions, the swelling behavior was evaluated with solvents that are able to dissolve the uncured rubber portion but not the thermoplastic component of the mixtures. All five systems showed swelling index values that were substantially less than the calculated “theoretical” values of swelling index. This was attributed to a caging effect of the thermoplastic component on the rubber phase, which restricts access of solvent and swelling of the rubber phase. In turn, this affects the solvent resistance of the blend. Some of the blends were evaluated by differential scanning calorimetry to assess the compatibility of the components in the blend. scanning electron microscopy was also used to determine the degree of compatibility of the two phases generated in the mixing process. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Analysis of the chondrogenic potential of human synovial stem cells according to harvest site and culture parameters in knees with medial compartment osteoarthritis
Authors: Nagase Tsuyoshi , Muneta Takeshi , Ju Young‐Jin , Hara Kenji , Morito Toshiyuki , Koga Hideyuki , Nimura Akimoto , Mochizuki Tomoyuki , Sekiya Ichiro
Published: April 2008

Objective

Synovial mesenchymal stem cells (MSCs) are an attractive cell source for cartilage regeneration because of their high chondrogenic ability. In this study, we examined the synovium of patients with medial compartment knee osteoarthritis (OA) to determine the proportion of MSCs in relation to cellular compartmentalization, and to identify the culture parameters that could affect the chondrogenic potential of synovial MSCs.

Methods

Human synovium was collected from 4 different harvest sites in the knees of patients with medial compartment OA. Each synovial tissue sample was divided into 2 parts, one for histologic assessment and the other for analysis of the cell size, surface epitopes, and chondrogenic potential of colony‐forming cells in vitro.

Results

The numbers of α‐smooth muscle actin–positive vessels and CD31+ endothelial cells were higher in the medial outer region than in the other regions of OA synovial tissue. The numbers of these cells correlated with the number of colony‐forming cells. In parallel with increasing duration of the preculture period, the size of the cells increased, while the chondrogenic potential decreased, and this was correlated with expression of CD90.

Conclusion

Medial compartment knee OA demonstrates variability in the distribution of vessels, which results in a varying distribution of MSCs. The preculture period should be utilized to assess both the potential for expansion and the chondrogenic potential of MSCs.
Autoantibodies to the translational suppressors T cell intracytoplasmic antigen 1 and T cell intracytoplasmic antigen 1–related protein in patients with rheumatic diseases: Increased prevalence in systemic lupus erythematosus and systemic sclerosis and correlation with clinical features
Authors: Jimenez‐Boj Esther , Kedersha Nancy , Tohidast‐Akrad Makiyeh , Karlhofer Franz M. , Stummvoll Georg , Zimmermann Christof , Ulrich Walter , Guiducci Serena , Hoefler Elisabeth , Aringer Martin , Schett Georg , Matucci‐Cerinic Marco , Smolen Josef S. , Steiner Günter
Published: April 2008

Objective

T cell intracytoplasmic antigen 1 (TIA‐1) and TIA‐1–related protein (TIAR) are involved in posttranscriptional regulation of the expression of tumor necrosis factor α (TNFα) and other proteins. Given the pivotal role of TNFα in chronic inflammatory diseases, this study was undertaken to analyze sera from patients with systemic autoimmune diseases for the presence of autoantibodies to TIA proteins and to investigate the expression of these proteins in inflamed tissue.

Methods

The presence of autoantibodies to TIA proteins in sera from 385 patients with rheumatic diseases and healthy controls was determined by immunoblotting using recombinant antigens. Expression of TIA proteins in skin and kidney tissue was analyzed by immunohistochemistry. Serum levels of TNFα were measured by enzyme‐linked immunosorbent assay.

Results

Autoantibodies to TIA‐1 and/or TIAR were detected in 61% of patients with systemic lupus erythematosus (SLE), 42% of patients with systemic sclerosis (SSc), 15–31% of patients with other rheumatic diseases, and 6% of healthy controls. Compared with patients negative for anti‐TIA antibody, anti‐TIA antibody–positive SLE patients had higher disease activity (P = 0.01), elevated antibodies to double‐stranded DNA (P = 0.0003), and increased serum TNFα levels (P = 0.018). In SLE patients, anti‐TIAR antibodies were associated with lupus nephritis (P = 0.02), while in patients with SSc, anti–TIA‐1 was associated with lung involvement (P = 0.02). Immunohistochemical analysis of skin and kidney tissue revealed aberrant expression of TIA proteins in skin lesions from SLE and SSc patients, as well as in glomerular cells from SLE patients.

Conclusion

Aberrant expression of TIA proteins in inflammatory tissue may lead to systemic autoantibody responses, particularly in SLE and SSc. Increased occurrence of anti‐TIA autoantibodies in patients with severe organ involvement may point to a possible pathogenetic role.
Mechanisms for cytotoxic effects of anti–tumor necrosis factor agents on transmembrane tumor necrosis factor α–expressing cells: Comparison among infliximab, etanercept, and adalimumab
Authors: Mitoma Hiroki , Horiuchi Takahiko , Tsukamoto Hiroshi , Tamimoto Yasuhiro , Kimoto Yasutaka , Uchino Ayumi , To Kentaro , Harashima Shin‐Ichi , Hatta Nobuaki , Harada Mine
Published: April 2008

Objective

Three anti–tumor necrosis factor α (anti‐TNFα) agents have been proved to be effective for rheumatoid arthritis (RA) and other inflammatory disorders. Infliximab and adalimumab have been generated as anti‐TNFα monoclonal antibodies, while etanercept is engineered from human type II TNF receptors. In spite of all 3 agents' equal efficacy for RA, both infliximab and adalimumab are effective for other diseases such as Crohn's disease and Wegener's granulomatosis, while etanercept is not. We undertook this study to understand the different clinical effects of these anti‐TNFα agents by analyzing their biologic activities on transmembrane TNFα.

Methods

Jurkat T cells stably expressing an uncleavable form of transmembrane TNFα were used for the following studies: 1) flow cytometric analysis of binding activities of anti‐TNF agents to cell surface transmembrane TNFα, 2) complement‐dependent cytotoxicity (CDC), 3) antibody‐dependent cell‐mediated cytotoxicity (ADCC) by using peripheral blood mononuclear cells, and 4) outside‐to‐inside (reverse) signal transduction through transmembrane TNFα estimated by apoptosis and cell cycle analysis using flow cytometry.

Results

All of the anti‐TNFα agents bound to transmembrane TNFα. Infliximab and adalimumab exerted almost equal CDC activities, while etanercept showed considerably lower activity. ADCC activities were almost equal among these 3 agents. Adalimumab and infliximab induced apoptosis and cell cycle arrest in transmembrane TNFα–expressing Jurkat T cells, reflecting an outside‐to‐inside signal transduction through transmembrane TNFα.

Conclusion

Three different anti‐TNF agents showed different biologic effects on transmembrane TNFα. This finding suggests that CDC and outside‐to‐inside signals by anti‐TNFα antibodies may explain the successful clinical efficacy of adalimumab and infliximab in Crohn's disease and Wegener's granulomatosis.
Predominance of cyclooxygenase 1 over cyclooxygenase 2 in the generation of proinflammatory prostaglandins in autoantibody‐driven K/BxN serum–transfer arthritis
Authors: Chen Mei , Boilard Eric , Nigrovic Peter A. , Clark Patsy , Xu Daigen , FitzGerald Garret A. , Audoly Laurent P. , Lee David M.
Published: April 2008

Objective

Prostaglandins (PGs) are found in high levels in the synovial fluid of patients with rheumatoid arthritis, and nonsteroidal blockade of these bioactive lipids plays a role in patient care. The aim of this study was to explore the relative contribution of cyclooxygenase (COX) isoforms and PG species in the autoantibody‐driven K/BxN serum–transfer arthritis.

Methods

The prostanoid content of arthritic ankles was assessed in ankle homogenates, and the importance of this pathway was confirmed with pharmacologic blockade. The presence of COX isoforms was assessed by Western blotting and their functional contribution was compared using COX‐1−/− and COX‐2−/− mice as well as isoform‐specific inhibitors. The relative importance of PGE2 and PGI2 (prostacyclin) was determined using mice deficient in microsomal PGE synthase 1 (mPGES‐1) and in the receptors for PGI2.

Results

High levels of PGE2 and 6‐keto‐PGF1α (a stable metabolite of PGI2) were detected in arthritic joint tissues, correlating strongly with the intensity of synovitis. Pharmacologic inhibition of PG synthesis prevented arthritis and ameliorated active disease. While both COX isoforms were found in inflamed joint tissues, only COX‐1 contributed substantially to clinical disease; COX‐1−/− mice were fully resistant to disease, whereas COX‐2−/− mice remained susceptible. These findings were confirmed by isoform‐specific pharmacologic inhibition. Mice lacking mPGES‐1 (and therefore PGE2) developed arthritis normally, whereas mice incapable of responding to PGI2 exhibited a significantly attenuated arthritis course, confirming a role of PGI2 in this arthritis model.

Conclusion

These findings challenge previous paradigms of distinct “housekeeping” versus inflammatory functions of the COX isoforms and highlight the potential pathogenic contribution of prostanoids synthesized via COX‐1, in particular PGI2, to inflammatory arthritis.
Outcomes of obese and nonobese patients undergoing revision total hip arthroplasty
Authors: Lübbeke Anne , Moons Karel G. M. , Garavaglia Guido , Hoffmeyer Pierre
Published: April 2008

Objective

To evaluate the effect of obesity on the incidence of adverse events (surgical site infection, dislocation, re‐revision, or ≥1 adverse event), functional outcome, residual pain, and patient satisfaction after revision total hip arthroplasty (THA).

Methods

We conducted a university hospital‐based prospective cohort study including 52 obese and 152 nonobese patients with revision THA performed between 1996 and 2006. We used incidence rates, rate ratios, and hazard ratios (HRs) to compare the incidence of events in obese and nonobese patients and in 4 body mass index (BMI) categories (<25, 25–29.9, 30–34.9, ≥35). Functional outcome and pain were measured 5 years postoperative using the Harris Hip Score.

Results

The incidence rate for ≥1 complication increased with rising BMI (1.8, 3.4, 10.3, and 17.9 cases/100 person‐years). The increase was small between normal and overweight patients (adjusted HR 1.5, 95% confidence interval [95% CI] 0.5, 4.7), significantly greater with BMI 30–34.9 (adjusted HR 4.5, 95% CI 1.4, 14.0), and most evident with BMI ≥35 (adjusted HR 10.9, 95% CI 2.9, 41.1). The adjusted HR for surgical site infection (obese versus nonobese) was 4.1 (95% CI 1.1, 15.0) and for dislocation 3.5 (95% CI 1.3, 9.3). Eighty patients had a followup visit at 5 years. Obese patients had moderately lower functional results and higher levels of residual pain, but patient satisfaction was almost similar.

Conclusion

Revision THA is technically challenging, particularly in obese patients, probably due to more difficult anatomic conditions. We found an increased risk of adverse events, notably surgical site infection and dislocation in these patients.
Measuring clinical enthesitis in psoriatic arthritis: Assessment of existing measures and development of an instrument specific to psoriatic arthritis
Authors: Healy Paul J. , Helliwell Philip S.
Published: April 2008

Objective

To assess currently available tools for measurement of enthesitis and to develop a new instrument specifically for use in psoriatic arthritis (PsA).

Methods

Twenty‐eight patients with PsA underwent clinical assessment over a period of 6 months after change of disease‐modifying therapy, usually to methotrexate. Measures of enthesitis included the Mander Enthesitis Index (MEI), the Maastricht Ankylosing Spondylitis Enthesitis Score, the Major index, and the Gladman index. Data from these assessments were used to develop a new enthesitis index, the Leeds Enthesitis Index (LEI).

Results

An iterative process of data reduction enabled derivation of the LEI index, which consisted of 6 sites: right and left Achilles insertions, medial femoral condyles, and lateral epicondyles of the humerus. All measures showed significant change from baseline but only the LEI and Gladman indices showed a large effect size. All indices demonstrated a floor effect (a score of 0 when the MEI is >0) but this was minimal for the LEI index. All indices correlated strongly with each other and other measures of disease activity.

Conclusion

The LEI is a new enthesitis index designed for use in PsA. It shows good test characteristics that suggest it will be a robust and reliable assessment tool. We suggest that it be adopted for use in any randomized controlled trials and longitudinal observation cohorts involving patients with PsA.
Confirmatory factor analysis of the Arthritis Impact Measurement Scales 2 short form in patients with rheumatoid arthritis
Authors: ten Klooster Peter M. , Veehof Martine M. , Taal Erik , van Riel Piet L. C. M. , van de Laar Mart A. F. J.
Published: April 2008

Objective

To examine the factorial validity of the short form Arthritis Impact Measurement Scales 2 (AIMS2‐SF) in patients with rheumatoid arthritis (RA).

Methods

Data were from a sample of 279 patients with active RA who completed the long form AIMS2 before starting treatment with tumor necrosis factor α–blocking agents. Confirmatory factor analyses were conducted to test and compare the fit of the currently used theoretical measurement model of the AIMS2‐SF, originally suggested for the long form AIMS2, and 2 alternative models based on previous exploratory research.

Results

A model with the physical dimension divided into upper and lower body limitations was superior to the current model, and both models provided a clearly better fit than a model without a separate symptom dimension. Under the restrictive assumption of uncorrelated error terms, none of the models achieved a consistent and acceptable fit as judged by several goodness‐of‐fit indices. Allowing error covariances between 6 pairs of items within the same dimension resulted in an improved and acceptable fit of both the current model and the model with a separate upper and lower body component.

Conclusion

This study generally supports the factorial validity of the AIMS2‐SF and suggests the use of separate scores for upper and lower body limitations. Further research is needed to resolve the issue of high error correlations associated with particular items.
Controlling kinesin motor proteins in nanoengineered systems through a metal‐binding on/off switch
Authors: Greene Adrienne C. , Trent Amanda M. , Bachand George D.
Published: April 2008

A significant challenge in utilizing kinesin biomolecular motors in integrated nanoscale systems is the ability to regulate motor function in vitro. Here we report a versatile mechanism for reversibly controlling the function of kinesin biomolecular motors independent of the fuel supply (ATP). Our approach relied on inhibiting conformational changes in the neck‐linker region of kinesin, a process necessary for microtubule transport. We introduced a chemical switch into the neck‐linker of kinesin by genetically engineering three histidine residues to create a Zn2+‐binding site. Gliding motility of microtubules by the mutant kinesin was successfully inhibited by ≥10 µM Zn2+, as well as other divalent metals. Motility was successfully restored by removal of Zn2+ using a number of different chelators. Lastly, we demonstrated the robust and cyclic nature of the switch using sequential Zn2+/chelator additions. Overall, this approach to controlling motor function is highly advantageous as it enables control of individual classes of biomolecular motors while maintaining a consistent level of fuel for all motors in a given system or device. Biotechnol. Bioeng. 2008;101: 478–486. © 2008 Wiley Periodicals, Inc.
Valorization of onion waste and by‐products: MCR‐ALS applied to reveal the compositional profiles of alcoholic fermentations of onion juice monitored by near‐infrared spectroscopy
Authors: González‐Sáiz José‐María , Esteban‐Díez Isabel , Rodríguez‐Tecedor Sofía , Pizarro Consuelo
Published: April 2008

The overall purpose of the project, of which this study is a part, was to examine the feasibility of onion waste as a support‐substrate for the profitable production of food‐grade products. This study focused on the efficient production of ethanol from worthless onions by transforming the onion juice into onion liquor via alcoholic fermentation with the yeast Saccharomyces cerevisiae. The onion bioethanol produced could be later used as a favorable substrate for acetic fermentation to finally obtain onion vinegar. Near‐infrared spectroscopy (NIRS), coupled with the multivariate curve resolution‐alternating least squares (MCR‐ALS) method, has been used to reveal the compositional and spectral profiles for both substrates and products of alcoholic fermentation runs, that is, total sugars, ethanol, and biomass concentration. The ambiguity associated with the ALS calculation was resolved by applying suitable inequality and equality constraints. The quality of the results provided by the NIR‐based MCR‐ALS methodology adopted was evaluated by several performance indicators, including the variance explained by the model, the lack of fit and the agreement between the MCR‐ALS achieved solution and the results computed by applying previously validated PLS reference models. An additional fermentation run was employed to test the actual predictive ability of the ALS model developed. For all the components resolved in the fermentation system studied (i.e., total sugars, ethanol, and biomass), the final model obtained showed a high predictive ability and suitable accuracy and precision, both in calibration and external validation, confirmed by the very good agreement between the ALS responses and the reference values (the coefficient of determination was, in all cases, very close to 1, and the statistics confirmed that no significant difference was found between PLS reference models and the MCR‐ALS methodology applied). Thus, the proven reliability of the MCR‐ALS model presented in this study, based only on NIR measurements, makes it suitable for monitoring of the key species involved in the alcoholic fermentation of onion juice, allowing the process to be modeled and controlled in real time. Biotechnol. Bioeng. 2008;101: 776–787. © 2008 Wiley Periodicals, Inc.
Der Eisbär: Postertier mit ungewisser Zukunft. Überlebensspezialist der Arktis
Authors: Breiter Matthias
Published: April 2008

Eisbären sind Überlebenskünstler, die zahlreiche Anpassungen sowohl in morphologischer Hinsicht als auch in Bezug auf ihre Verhaltensweisen aufweisen, um in der Arktis zu überleben. Noch heute ist unser Verständnis von den Tieren lückenhaft und zum Teil von Vorurteilen behaftet. Die Schwierigkeiten, die Tiere in ihrem natürlichen Lebensraum auf dem Packeis zu beobachten, spielen dabei eine große Rolle. Ein weiter Grund ist, dass uns Menschen der arktische Lebensraum prinzipiell fremd ist und lebensfeindlich erscheint. Dadurch haben wir die Tendenz, Aspekte, die uns Probleme bereiten, wie die Kälte, überzubewerten, und andere Aspekte, wie den Wasserhaushalt, kaum zu beachten. Die Zukunft der Eisbären wird davon abhängen, dass wir ihre Bedürfnisse besser verstehen, um eine Koexistenz zu ermöglichen. Die Problematik der industriellen Nutzung der Arktis, einer Begleiterscheinung der globalen Erwärmung, findet zu wenig Beachtung. Die jeweiligen verantwortlichen Regierungen schenken in dieser Hinsicht bisher wirtschaftlichen Interessen wesentlich mehr Aufmerksamkeit als Umweltfragen.
Constantin Mereschkowsky
Authors: Höxtermann Ekkehard
Published: April 2008

Constantin Mereschkowsky gilt als Begründer der Symbiogenesetheorie der Entstehung eukaryoter Zellen (1905). Zu Lebzeiten umstritten, gerieten seine Ideen weitgehend in Vergessenheit und erfuhren erst in den 1990er Jahren eine Renaissance. Die Wiederentdeckung des Werkes offenbarte zugleich das unstete Leben eines heimatlosen Mannes, das tragisch endete.
Neues Unterrichtsmaterial des Nationalen Genomforschungsnetzes auf CD‐ROM
Authors: Krüger Olaf
Published: April 2008

Das komplexe Wissen zur Humangenomforschung fundiert und trotzdem anschaulich und spannend zu vermitteln, ist eine Herausforderung für jeden Lehrer. Damit dieses Kunststück noch besser gelingt, hat das Nationale Genomforschungsnetz (NGFN, www.ngfn.de) das Unterrichtsmaterial “GENial einfach!” entwickelt, das kostenlos erhältlich ist.
Synthesis and Screening of an Oroidin Library against Pseudomonas aeruginosa Biofilms
Authors: Richards Justin J. , Ballard T. Eric , Huigens Robert W. , Melander Christian
Published: April 2008

A 50‐compound library based on the marine natural product oroidin was synthesized and assayed for anti‐biofilm activity against PAO1 and PA14, two strains of the medically relevant γ‐proteobacterium Pseudomonas aeruginosa. Through structure–activity relationship (SAR) analysis of analogues based on the oroidin template, several conclusions can be drawn as to what structural properties of the synthetic derivatives are necessary to elicit a biological response. Notably, the most active analogues identified were those that contained a 2‐aminoimidazole (2‐AI) motif and a dibrominated pyrrolecarboxamide subunit. Here we disclose the synthesis and subsequently determined biological activity of this unique class of compounds as inhibitors of biofilm formation that have no direct antibiotic effect.
Reactors for Fischer‐Tropsch Synthesis
Authors: Guettel R. , Kunz U. , Turek T.
Published: April 2008

The Fischer‐Tropsch synthesis was discovered in Germany in the 1920s and has since been developed to industrial scale within a relatively short period of time. In the 21st century, the process is undergoing a renaissance, because an increasing fraction of liquid fuels will have to be produced from alternative raw materials like natural gas, coal or biomass in the future. On industrial scale, multitubular and bubble column reactors are used for this highly exothermic reaction. Due to several disadvantages of both reactor systems, new concepts are presently investigated. For intensification of mass transfer properties of multiphase reactors, alternative catalyst geometries like honeycombs, structured packings or foams are discussed. High catalyst utilization and isothermal operating conditions can be achieved in microstructured reactors. Furthermore, several membrane reactor concepts are under investigation. After an introduction to historical development and state of the art of Fischer‐Tropsch reactors, chances and challenges of new reactor technologies will be discussed.
Fuels and Fuel Cells: The “Right Way” from Fuels to Fuel Gas
Authors: Hennings U. , Brune M. , Wolf M. , Reimert R.
Published: April 2008

Fuel cells are considered for various applications as well as in connection with the use of several types of energy feedstocks, both fossil and renewable. Large and very particular challenges arise from the design of the fuel gas supply in connection with envisioned applications and different sorts of fuels. The design of the fuel gas supply must meet the requirements posed by the type of raw fuel, the conceived application and the type of fuel cell employed. In this work, the resulting large number of possible combinations is summarized by a graph, i.e., the “fan”. The graphic description is explained by means of selected examples.
Biofuels for Automobiles – An Overview
Authors: Schaub G. , Vetter A.
Published: April 2008

Due to increasing oil prices and climate change concerns, biofuels have become more important as potential alternative energy sources. It is an open question as to which types of biofuels have the best yield potentials, characteristic properties and environmental consequences for providing the largest contribution to future energy requirements. Apart from the quality aspects, the question of quantity is very important, i.e., yields of biomass raw materials from agriculture and forestry as well as the conversion efficiencies/yields of the conversion process to automotive fuels. The most widely used biofuel forms today are fatty acid methyl esters and ethanol. However, in the future it is possible that synthetic hydrocarbons and hydrogen, produced via biotechnological or chemical processes may become feasible as fuel sources. Limitations in quantity are caused by net productivities of photosynthesis, which are limited by several factors, e.g., by the supply of water, limited availability of land, and conversion losses. As a consequence, biofuels as they exist can only contribute to a limited extent to securing raw material supplies for energy requirements in the future. Efficiency improvements in processing technologies and changes in consumer behavior and attitude will also be required.
Succinic Acid: A New Platform Chemical for Biobased Polymers from Renewable Resources
Authors: Bechthold I. , Bretz K. , Kabasci S. , Kopitzky R. , Springer A.
Published: April 2008

Succinic acid is predicted to be one of the future platform chemicals that can be derived from renewable resources. The improvements in biotechnological succinic acid production are presented. Chemical conversion pathways to γ‐butyrolactone, tetrahydrofuran, 1,4‐butanediole, and pyrrolidones are reviewed. An overview of possible new biopolymers (e. g. polyesters, polyamides, and poly(ester amide)s) based on succinic acid and its derivatives is given. Nevertheless, industrial processes using purified succinic acid from fermentation broths are not state of the art yet. Further improvements are needed until succinic acid‐based chemical production will be economically favorable.
Fischer‐Tropsch Catalysts for the Biomass‐to‐Liquid (BTL)‐Process
Authors: van Steen E. , Claeys M.
Published: April 2008

The Fischer‐Tropsch synthesis is at the heart of the Biomass‐to‐Liquids (BTL) process. Feasibility studies published in open literature typically consider cobalt‐based catalysts for the Fischer‐Tropsch synthesis. Here, we present an overview on the history and development up until the present for both cobalt‐ and iron‐based Fischer‐Tropsch catalysts. The role of the support material and various other additives to the catalyst formulation are discussed in detail with regard to activity, catalyst deactivation, and selectivity. Tentative explanations for e.g. the observed size dependency in cobalt‐based catalysts and phase transformations in iron‐based Fischer‐Tropsch catalysts are offered. The productivity of cobalt‐based catalysts at high conversion level is currently higher than that of iron‐based catalysts. Nevertheless, it is argued that iron‐based catalysts may be an attractive option for the BTL‐process, since it is much cheaper, impacting on the cost of the process due to inevitable process set‐ups in industrial operation. Improvement of current iron‐based catalysts is however desired.
Direct Liquefaction of Biomass
Authors: Behrendt F. , Neubauer Y. , Oevermann M. , Wilmes B. , Zobel N.
Published: April 2008

Reserves of fossil primary energy carriers are limited. Consequently liquid secondary energy carriers especially for mobile applications made from fossil reserves will not carry on forever but need to be replaced in a not‐to‐far future. Two substitution strategies are currently under investigation – the use of oil from plant seeds either directly or after chemical modification (biodiesel) or the gasification of complete plants, use of the product gases (mainly CO and H2) in a Fischer‐Tropsch process with subsequent refining. A third possible pathway would be the so‐called direct liquefaction, i.e., the conversion of complete plants into liquid fuels without gasification. This process is discussed and various technical implementations are critically evaluated in the present paper.
Motor Fuels From Biomass Pyrolysis
Authors: Barth T. , Kleinert M.
Published: April 2008

Different pyrolysis techniques for converting solid biomass material into liquid fuels that can be used in combustion motors are described and compared. The techniques include fast pyrolysis, pyrolysis in aqueous reaction media and a newly developed process based on a hydrogen donating solvent system and used for converting residual lignin after production of lignocellulosic ethanol production to liquids. New data from pyrolysis in liquid reaction media is presented and discussed. The quality of the oil as produced in the pyrolysis step is evaluated, and the range of different possible applications is emphasized.
Oxoanion Binding by Guanidiniocarbonylpyrrole Cations in Water: A Combined DFT and MD Investigation
Authors: Moiani Davide , Cavallotti Carlo , Famulari Antonino , Schmuck Carsten
Published: April 2008

Structures and properties of nonbonding interactions involving guanidinium‐functionalized hosts and carboxylate substrates were investigated by a combination of ab initio and molecular dynamics approaches. The systems under study are on one hand intended to be a model of the arginine–anion bond, so often observed in proteins and nucleic acids, and on the other to provide an opportunity to investigate the influence of molecular structure on the formation of supramolecular complexes in detail. Use of DFT calculations, including extended basis sets and implicit water treatment, allowed us to determine minimum‐energy structures and binding enthalpies that compared well with experimental data. Intermolecular forces were found to be mostly due to electrostatic interactions through three hydrogen bonds, one of which is bifurcate, and are sufficiently strong to induce a conformational change in the ligand consisting of a rotation of about 180° around the guanidiniocarbonylpyrrole axis. Free binding energies of the complexes were evaluated through MD simulations performed in the presence of explicit water molecules by use of the molecular mechanics Poisson–Boltzmann solvent accessible surface area (MM‐PBSA) and linear interaction energy (LIE) approaches. LIE energies were in quantitative agreement with experimental data. A detailed analysis of the MD simulations revealed that the complexes cannot be described in terms of a single binding structure, but that they are characterized by a significant internal mobility responsible for several low‐energy metastable structures.
A Case of anti Carbolithiation of Alkynes Resulting from Intramolecular Lithium Coordination
Authors: Fressigné Catherine , Girard Anne‐Lise , Durandetti Muriel , Maddaluno Jacques
Published: April 2008

The mechanism of the intramolecular carbolithiation of lithiated propargylic ether 2 has been investigated both experimentally and theoretically. The results show that the action of one equivalent of n‐butyllithium on 1 is sufficient to trigger halogen–lithium exchange and the subsequent heterocyclization step. Interestingly, the reaction stops at the stage of dihydrobenzofuran 6; no spontaneous elimination of lithium ethylate was observed. The fact that the E configuration of this adduct was exclusively produced suggests that the reaction proceeds by following an unprecedented anti addition on the alkyne. According to DFT calculations, this unexpected outcome is related to the intramolecular coordination of the lithium by one oxygen atom of the terminal acetal appendage: the O–Li interaction, which persists all along the ring‐closure process, drives the cation to the E site of the final olefin. The calculations also show that in the absence of this coordination (as in conformers B and C of acetal 2), the Z olefin that results from a classical syn addition of the aryllithium should be obtained. The experiments were repeated with allene 1 d. In this case, one equivalent of n‐butyllithium suffices to trigger not only the exchange and the cyclization, but also the final elimination of lithium ethoxide. The DFT results indicate that the intramolecular addition of the original aryllithium on the central carbon atom of the allene 2 b yields the expected benzofuran skeleton 3 b, which bears a lithiated lateral chain at the 3‐position. Both cyclizations go through low‐lying transition states, as is expected for rapid reactions at low temperature.
Cowpea Mosaic Virus Capsid: A Promising Carrier for the Development of Carbohydrate Based Antitumor Vaccines
Authors: Miermont Adeline , Barnhill Hannah , Strable Erica , Lu Xiaowei , Wall Katherine A. , Wang Qian , Finn M. G. , Huang Xuefei
Published: April 2008

Immunotherapy targeting tumor cell surface carbohydrates is a promising approach for cancer treatment. However, the low immunogenecity of carbohydrates presents a formidable challenge. We describe here the enhancement of carbohydrate immunogenicity by an ordered display on the surface of the cowpea mosaic virus (CPMV) capsid. The Tn glycan, which is overexpressed on numerous cancer cell surfaces, was selected as the model antigen for our study. Previously it has been shown that it is difficult to induce a strong T cell‐dependent immune response against the monomeric form of Tn presented in several ways on different carriers. In this study, we first synthesized Tn antigens derivatized with either a maleimide or a bromoacetamide moiety that was conjugated selectively to a cysteine mutant of CPMV. The glycoconjugate was then injected into mice and pre‐ and post‐immune antibody levels in the mice sera were measured by enzyme‐linked immunosorbant assays. High total antibody titers and, more importantly, high IgG titers specific for Tn were obtained in the post‐immune day 35 serum, suggesting the induction of T cell‐dependent antibody isotype switching by the glycoconjugate. The antibodies generated were able to recognize Tn antigens presented in their native conformations on the surfaces of both MCF‐7 breast cancer cells and the multidrug resistant breast cancer cell line NCI‐ADR RES. These results suggest that the CPMV capsid can greatly enhance the immunogenicity of weak antigens such as Tn and this can provide a promising tool for the development of carbohydrate based anti‐cancer vaccines.
Chiral Bisphosphazides as Dual Basic Enantioselective Catalysts
Authors: Naka Hiroshi , Kanase Nobuhiko , Ueno Masahiro , Kondo Yoshinori
Published: April 2008

Chiral bisphosphazides complexed with lithium salts efficiently catalyze the direct enantioselective 1,4‐addition of dialkyl malonates to acyclic enones. Spectroscopic studies on the stoichiometry of the bisphosphazide and lithium salt have indicated the formation of a 1:1 species as the active enantioselective catalyst. It is suggested that the catalyst generates a complex of the protonated phosphazide and the chiral nucleophile as the key intermediate. The phosphazide moiety appears to be a promising dual basic functionality for stereo‐ and chemoselective catalytic transformations.
Selective Formation of 2‐Imidazolines and 2‐Substituted Oxazoles by Using a Three‐Component Reaction
Authors: Elders Niels , Ruijter Eelco , de Kanter Frans J. J. , Groen Marinus B. , Orru Romano V. A.
Published: April 2008

Selective formation of 2H‐2‐imidazolines and 2‐substituted oxazoles by using a multicomponent reaction of amines, either aldehydes or ketones, and α‐acidic isocyano amides or esters is described. By selecting the appropriate solvent, AgI or CuI catalyst, or by employing a weak Brønsted acid, the product formation can be fully controlled and directed quantitatively to the desired heterocyclic scaffold. The described experimental procedures not only significantly increase the scope of compatible inputs for this complexity‐generating three‐component reaction, but also allow for considerable chemical diversity: At least four diversity points in two distinct scaffolds can be exploited in this way.
Ein Gleichnis für den Chemieunterricht
Authors: Richter Harald , Schmidkunz Heinz , Kreher Richard P.
Published: April 2008

Steht im Chemieunterricht der Sekundarstufe 2 das Thema Reaktionskinetik an, dann sollten auch Konkurrenzreaktionen in die Unterrichtsgestaltung einbezogen werden. Zum Einstieg in dieses Thema empfiehlt es sich, an einen gängigen (meist bereits in der Sekundarstufe 1 eingeführten) Sprachgebrauch zu erinnern: „Es gibt ungesättigte Kohlenwasserstoffe, die durch vollständige Addition von Wasserstoff oder Brom gesättigt werden.”︁ Bei einer verständlichen Planung der Lehrkräfte können die animistischen Hintergründe dieser Redensart Schüler und Schülerinnen motivieren, die Reaktivitäten von zwei verschiedenen Alkenen bei einer Konkurrenzreaktion mit Spannung zu betrachten.
Das Projekt Forscher Ferien
Authors: Demuth Reinhard , Efler‐Mikat Daniela , Kleinert Katrin
Published: April 2008

Mit dem Forscher Ferien‐Projekt ist der Versuch unternommen worden, eine Kompensation von Lerndefiziten durch außerschulische Lernangebote vorzunehmen. Dieser Beitrag stellt das Projekt vor und gibt einen ersten Erfahrungsbericht über die „Forscher Ferien”︁.
Two Cases with Similar Pseudoaneurysms but Different Outcomes
Authors: Bildirici Ulaş , Agacdiken Aysen , Ural Ertan , Kahraman Goksel , Komsuoglu Baki
Published: April 2008

The pseudoaneurysm is a rare cardiac pathology, in which the left ventricular free wall ruptures and the pericardium surrounds the rupture in combination with thrombus and inflammation and thus prevents the development of a hemopericardium. Left ventricular pseudoaneurysm may remain silent unless it gives rise to cardiac tamponade, collapse, and finally sudden death. In this case report, we present two cases with left ventricular pseudoaneurysms in the same area. One of them had a stable outcome and the other had a fatal outcome. Copyright © 2008 Wiley Periodicals, Inc.
Theory of diffraction from eukaryotic flagellar axonemes
Authors: Iwamoto Hiroyuki
Published: April 2008

Existing theories for diffraction from cylindrically symmetrical and helical objects are applied to the axonemes of eukaryotic flagella and cilia, motile organelles responsible for locomotion of cells, transportation of food and mucus, etc. Each axoneme has a scaffold of microtubules arranged in the “9 + 2” scheme. Motor proteins dynein and other proteins are associated with the scaffold with apparent axial periodicities, and their exact arrangement would be best explored by X‐ray diffraction. Here, various symmetries are assumed (helical and nonhelical) in the arrangement of these proteins, and the reflections that will emerge are predicted, hereby providing a practical means to analyze diffraction patterns currently being recorded in the latest synchrotron radiation facilities. Cell Motil. Cytoskeleton 2008. © 2008 Wiley‐Liss, Inc.
Molecular and developmental biology of the hemangioblast
Authors: Xiong Jing‐Wei
Published: April 2008

The hemangioblast hypothesis was proposed a century ago. The existence of hemangioblasts is now demonstrated in mouse and human embryonic stem cell (ESC) ‐derived embryoid bodies (EBs), in the mouse and zebrafish gastrula, and in adults. The hemangioblast is believed to derive from mesodermal cells, and is enriched in the Bry+Flk1+ and Flk1+Scl+ cell populations in EBs and in the posterior primitive streak of the mouse gastrula and in the ventral mesoderm of the zebrafish gastrula. However, recent studies suggest that the hemangioblast does not give rise to all endothelial and hematopoietic lineages in mouse and zebrafish embryos. Although several signaling pathways are known to involve the generation of hemangioblasts, it remains largely unknown how the hemangioblast is formed and what are the master genes controlling hemangioblast development. This review will summarize our current knowledge, challenges, and future directions on molecular and developmental aspects of the hemangioblast. Developmental Dynamics 237:1218–1231, 2008. © 2008 Wiley‐Liss, Inc.
Synthesis of Enantiopure Ruthenium Tricarbonyl Complexes of a Bicyclic Cyclopentadienone Derivative
Authors: Kim Min‐soo , Lee Jun Won , Lee Jae Eun , Kang Jahyo
Published: April 2008

(–)‐Menthone was converted stereoselectively into 3‐menthylpropargyl alcohol 8 in several steps and subsequently converted into enantiopure cyclopentadienone ruthenium carbonyl complexes. In the malonate cases, ruthenacycle 15 was also formed during the cyclization reaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Transition‐Metal‐Free Synthesis of Perdeuterated Imidazolium Ionic Liquids by Alkylation and H/D Exchange
Authors: Giernoth Ralf , Bankmann Dennis
Published: April 2008

Economic, transition‐metal‐free syntheses of partially or completely deuterated imidazolium ionic liquids (ILs) were developed. Double alkylation starting from imidazole afforded side‐chain deuterated imidazolium ionic liquids, which subsequently were fully deuterated by H/D‐exchange on the cation ring. Isotopic exchange was studied for a range of ionic liquids, solvents and bases. Here, the presence of small amounts of basic impurities was found to significantly affect the exchange behaviour.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
The Tetracyanoquinodimethane Motif in Overcrowded Bistricyclic Aromatic Enes: Avoiding Thermochromism
Authors: Pogodin Sergey , Suissa Michal Rachel , Levy Amalia , Cohen Shmuel , Agranat Israel
Published: April 2008

The overcrowded bistricyclic aromatic enes (BAEs) [10‐[10‐(dicyanomethylene)‐9(10H)‐anthracenylidene]‐9(10H)‐anthracenylidene]propanedinitrile (7) and [10‐[10‐oxo‐9(10H)‐anthracenylidene]‐9(10H)‐anthracenylidene)]propanedinitrile(8) were synthesized by a condensation of bianthrone (2) with malononitrile in the presence of TiCl4 and pyridine. The crystal and molecular structure of 7 were determined. It crystallizes in two polymorphic forms, belonging to the space groups P21/c and P21/n. DFT calculations of 7 and 8 show that the overcrowding due to introducing dicyanomethylene substituents to 10 and 10′ positions is more pronounced in the twisted conformations, decreasing their stabilities. The enthalpy differences between the anti‐folded and the lowest lying twisted conformations in BAEs 7 and 8 are 61.3 and 42.3 kJ/mol, respectively. In accordance with theory, BAEs 7 and 8 do not exhibit thermochromic behavior. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Application of capillary zone electrophoresis for separation of water‐soluble gold monolayer‐protected clusters
Authors: Lo Chung Keung , Paau Man Chin , Xiao Dan , Choi Martin M. F.
Published: April 2008

An effective capillary electrophoretic technique for separating samples of negatively charged, polydisperse, water‐soluble gold monolayer‐protected cluster (Au MPC) protected by monolayers of N‐acetyl‐L‐cysteine has been developed. The separation mechanisms of the Au MPC in CZE suggest that the larger core sizes Au MPC emerge first from the capillary. The electrophoretic separation depends on pH, buffer concentration, and organic modifiers. The addition of aliphatic alcohols to the run buffer can improve the separation of Au MPC by reducing the EOF and changing the selectivity between the Au MPCs. The enhancement of resolution is attributed to the more significant difference in the charge‐to‐size ratio between the Au MPCs. The run buffer containing 20 v/v % ethanol provides the best separation for water‐soluble Au MPC. Our proposed CE method provides a powerful tool to evaluate and separate the water‐soluble Au MPC products.
Capillary electrophoresis chemiluminescent detection system equipped with a two‐step postcolumn flow interface for detection of some enkephalin‐related peptides labeled with acridinium ester
Authors: Guo Longhua , Qiu Bin , Jiang Yingyan , You Zuyao , Lin Jin‐Ming , Chen Guonan
Published: April 2008

Despite its low equipment cost and simple design, as one of the sensitive detectors for CE, the chemiluminescence (CL) detector was less developed compared to the detectors of MS and LIF. The main reasons were the limitation of CL reagents, the repeatability problems and the relatively low sensitivity compared to LIF. In this paper, a highly sensitive CE‐CL detection system was developed for detection of some enkephalin‐related peptides labeled with acridinium ester. A new detection interface was designed for CE with CL detection of acridinium ester and its labeled analytes. The interface included two sections: one was used to acidify the capillary outflow so that the corresponding acridinium pseudo‐base form can be changed into acridinium ester form by adding excess acid to the system; the other was designed to provide a suitable solution to produce the CL from acridinium ester. The effect factors, such as pH, the concentration of reaction reagents and the flow rates of the reagents, were investigated. The results showed that acridinium ester had similar CL properties in this interface when pH values of CE BGE were changed from 2.0 to 10.8. The interface was used to detect acridinium ester and three acridinium ester‐labeled enkephalin‐related peptides, the corresponding LODs were found to be in the attomole range. This CL detection system proved to be of high sensitivity, good repeatability, and relatively low cost.