bluuebunny/crossref_metadata_2025 huggingface dataset:
In situ FT-IR Investigation of Formic Acid Adsorption on Reduced and Reoxidized Copper Catalysts
Authors: Millar Graeme J. , Newton David , Bowmaker Graham A. , Cooney Ralph P.
Published: May 2005

An in situ infrared cell capable of studying reactions over heterogeneous catalysts in the temperature range 77 to 773 K has been designed. In particular, the adsorption of formic acid on a model Cu/SiO2 methanol synthesis catalyst was investigated. Exposure of a reduced copper surface to formic acid at 300 K resulted in the formation of both formic acid molecules, which were ligated to the copper catalyst, and chemisorbed bidentate copper formate species. Under temperature-programming conditions, the bidentate species displayed a maximum rate of desorption at 433 K, which correlates to a desorption activation energy of 120 kJ mol−1. In contrast, on the reoxidized catalyst, unidentate formate species were preferentially formed. These exhibited a maximum rate of desorption at a temperature of 408 K, and a desorption activation energy of 113 kJ mol−1. A mechanism was postulated to explain this behavior, and evidence was presented to show that useful kinetic data can be obtained for desorption from a catalyst in the form of a pressed disk.
Chemical Mechanism and Efficiency of the Sulfur Chemiluminescence Detector
Authors: Benner Richard L. , Stedman Donald H.
Published: May 2005

The sulfur chemiluminescence detector (SCD) is a sensitive, highly selective sulfur detection system based on reaction in hydrogen/air combustion followed by extraction and low-pressure chemiluminescence. This report documents investigations into the fundamental chemical processes occurring in the SCD. The conclusion from this work is that ozone reacts with sulfur monoxide (SO) to form electronically excited SO2. A gas-phase titration of the SO formed indicates that approximately four of every 1000 sulfur-containing molecules entering the flame arrive at the reaction cell as SO. This new understanding of the SCD will allow future studies to concentrate on optimization of instrumental performance based on the appropriate chemical mechanism.
New Cell for the Fourier Transform Raman Analysis of Fiber and Textile Samples
Authors: Church Jeffrey S. , Davie Ashley S. , James David W. , Leong Wah-Hing , Tucker Daryl J.
Published: May 2005

A new cell has been developed for the measurement of fiber and textile samples using FT-Raman spectroscopy. It improves the strength of the signal over that of conventional solid cells by the compression of the samples to be analyzed and the use of a mirror to reflect scattered radiation back out of the cell and into the collection lens of the spectrometer. The new cell also eliminates the problem of cell window material interfering with the sample spectrum, since the laser passes through a windowless aperture to reach the sample. This consideration is particularly important when spectra are being obtained from weakly scattering samples. The design, optimization, and use of the new cell are presented. The performance of the new cell in terms of improvements in signal-to-noise ratio and elimination of spectral artifacts is compared to that of other conventional sampling techniques. Significant improvements in spectral quality were obtained from both natural and synthetic fiber and textile samples.
Monitoring Hydrofluoric Acid Activity by Vapor-Phase Infrared Spectroscopy
Authors: Brenneman Keith R. , Donohoe Robert J.
Published: May 2005

Infrared spectra of the vapor phase over solutions approximating those used in the dissolution of plutonium, typically 10 M in nitric acid and 0.2 M in hydrofluoric acid, reveal that the hydrofluoric acid (HF) activity can be monitored in a facile and noninvasive manner. The amount of vaporized HF is strongly dependent upon the nitric acid content; the vapor-phase HF content over a series of solutions in which the HF concentration is held constant at 0.5 M increases by a factor of nearly 25 as the HNO3 concentration is increased from 0 to 14 M. This effect is due to changes in the HF activity and is not a result of changes in the heat of vaporization, which was measured (by van't Hoff plots) to be 9.4 ± 0.6 kcal/mole for 16 mock process solutions ranging from 0.01 to 0.1 M HF and 8 to 14 M HNO3. This result demonstrates that spectroscopic methods can use the vaporization of an analyte to measure the activity rather than the concentration.
Use of FT-IR for the Quantification of Water in Biomolecules
Authors: Iwaoka Teiki , Tabata Fumiko , Tsutsumi Shinya
Published: May 2005

Water (10−3 mg H2O in 1 mg of biopolymer) was extracted from biological compounds with acetonitrile and determined by FT-IR spectrometry with the use of a KBr transmission cell. A nitrogen-gas-purged glove box was employed during the extraction to avoid errors due to water absorption from ambient laboratory air. The subtractive compensation for concomitant water in acetonitrile was further accomplished by using a reference spectrum of acetonitrile kept under the same experimental conditions as those for preparing the acetonitrile extracts of water from the testing samples. This technique was applied to the quantification of water in peptides and enzymes. The advantages of this technique over the Karl Fisher titration are discussed, along with measurements for loss of weight on drying in vacuo.
Isotopic Chromatographic Spectral Analysis of Inorganic Gases
Authors: Funtov Valery N. , Nemets Valeriy M. , Petrov Arcadiy A. , Soloviov Anatoliy A.
Published: May 2005

The possibilities of the hyphenated isotopic chromatographic spectral method (ICSM) of inorganic gas analysis are considered. The technique allows detection of both the individual element and molecular admixtures. For evaluation of the total content of the element, isotope balancing and conversion of all components containing this element into a molecular compound more suitable for chromatographic isolation and spectroscopic detection are used. High sensitivity is achieved by preconcentration of admixtures with the simultaneous monitoring of possible distortions of the sample composition at all stages of analysis by means of the introduction of a rare stable isotope. The fields of application are the analysis of high-purity gases, evaluation of the total contents of individual elements, metrological tasks of apparatus calibration, and so on. The method does not need reference samples prepared from the analyzed gaseous matrices for the calibration itself.
Quantitative Analysis of Kaolinite/Silica and Kaolinite/KBr Mixtures by Photoacoustic FT-IR Spectroscopy
Authors: Saffa A. M. , Michaelian K. H.
Published: May 2005

Photoacoustic FT-IR spectroscopy was used to quantify kaolinite in binary mixtures with KBr and silica, with the use of a linear relationship between the reciprocals of photoacoustic intensity and kaolinite concentration. The method is valid for both dilute and concentrated mixtures; an average error of 12% was obtained for kaolinite concentrations ranging from 15 to 80%. The technique thus compares favorably with more common approaches that require low analyte concentrations. It is concluded that quantitative photoacoustic infrared spectroscopy is feasible provided that the magnitude of the product of thermal diffusion length and absorption coefficient is taken into account.
New Accessory for Characterizing Optical Fibers with an FT-IR Spectrometer
Authors: Lowry S. , May T. , Bornstein A. , Weissman Y. , Harman R. , Tugenthaft I.
Published: May 2005

An accessory has been designed for FT-IR spectroscopy that can be used to measure the optical properties of fiber-optic cables or serve as an interface for remote sensing probes that use fiber optics. This accessory utilizes compound parabolic concentrators (CPCs) to focus the energy from the spectrometer into the optical fiber and to also refocus the energy returning to the spectrometer onto the detector. The design was optimized for the high acceptance angle of chalcogenide mid-IR fibers. However, the use of nonimaging concentrators yields an all-reflecting system that can be used to characterize fibers with different spectral transmission ranges. This accessory has been used to investigate the spectral response, cladding effects, and impurities in various optical fibers.
Use of an Optical-Fiber-Based Biosensor to Study the Interaction of Blood Proteins with Solid Surfaces
Authors: Poirier Michelle A. , Lopes Teresa , Singh Bal Ram
Published: May 2005

An optical fiber-based laser biosensor has been used to investigate adsorption of blood lipoproteins and immunoglobulin G to the glass optical-fiber surface. While lipoproteins readily interact (adsorb) with unmodified optical-fiber surface, immunoglobulin G does not bind to the glass surface at a concentration of 5 μg/mL. However, upon glass surface modification with silane, immunoglobulin G binds significantly to the optical fiber. High-density lipoproteins and low-density lipoproteins show a differential interaction with the glass surface, and their interaction was altered upon modification of the glass surface with cholesterol. With these results in mind, the utility of the biosensor for the study of protein interaction with biorelevant surfaces has been outlined.
Perlecan, a Basement Membrane-type Heparan Sulfate Proteoglycan, in the Enamel Organ: Its Intraepithelial Localization in the Stellate Reticulum
Authors: Ida-Yonemochi Hiroko , Ohshiro Kazufumi , Swelam Wael , Metwaly Hamdy , Saku Takashi
Published: May 2005

The localization and biosynthesis of perlecan, a basement membrane-type heparan sulfate proteoglycan, were studied in developing tooth germs by using murine molars in neonatal and postnatal stages and primary cultured cells of the enamel organ and dental papilla to demonstrate the role of perlecan in normal odontogenesis. Perlecan was immunolocalized mainly in the intercellular spaces of the enamel organ as well as in the dental papilla/pulp or in the dental follicle. By in situ hybridization, mRNA signals for perlecan core protein were intensely demonstrated in the cytoplasm of stellate reticulum cells and in dental papilla/pulp cells, including odontoblasts and fibroblastic cells in the dental follicle. Furthermore, the in vitro biosyntheses of perlecan core protein by the enamel organ and dental papilla/pulp cells were confirmed by immunofluorescence, immunoprecipitation, and reverse transcriptase-polymerase chain reaction. The results indicate that perlecan is synthesized by the dental epithelial cells and is accumulated in their intercellular spaces to form the characteristic stellate reticulum, whose function is still unknown.
Temporal Expression of Alpha–Smooth Muscle Actin and Drebrin in Septal Interstitial Cells during Alveolar Maturation
Authors: Yamada Mie , Kurihara Hidetake , Kinoshita Katsuyuki , Sakai Tatsuo
Published: May 2005

In rat lung, the definitive alveoli are established during development by the outgrowth of secondary septa from the primary septa present in newborn; however, the mechanism of alveolar formation has not yet been fully clarified. In this study, we characterize the septal interstitial cells in developing alveoli. During the perinatal period, alpha-SMA–containing slender cells were found in the primitive alveolar septa. Alpha-SMA–containing cells were detected at the tips of the septa until postnatal day 21, when the alveolar formation was almost completed, but disappeared in adult. Immunoelectron microscopy demonstrated that alpha-SMA is localized mainly in the cellular protrusions, which are connected with the elastic fibers around the interstitial cells. Developmentally regulated brain protein (drebrin) is also located in the cell extensions containing alpha-SMA in immature alveolar interstitial cells. In adult lung, alpha-SMA–positive cells are located only at the alveolar ducts but are not found in the secondary septa. Desmin is expressed only in alpha-SMA–containing cells at the alveolar ducts but not in those at the tip of alveolar septa. These results suggest that a part of the septal interstitial cells are temporarily alpha-SMA– and drebrin-positive during maturation. Alpha-SMA– and drebrin-containing septal interstitial cells (termed septal myofibroblast-like cells) may play an important role in alveolar formation.
Pep-1 as a Novel Probe for the In Situ Detection of Hyaluronan
Authors: Zmolik Jessica M. , Mummert Mark E.
Published: May 2005

Hyaluronan (HA) is expressed by most tissues, including skin. Localization of HA in the skin is assessed by histology with HA-binding protein (HABP) serving as the probe. Reports have suggested that HA expression in skin is altered in a number of diseases. However, interlaboratory variations in HABP staining profiles, even in normal skin, suggest a need to standardize methods and/or identify new probes. We report the staining patterns of a HA-binding peptide (termed “Pep-1”) in human and mouse skin. After acetone fixation, Pep-1 stained HA in the intercellular spaces of the epidermis, whereas staining in the dermis was weak and diffuse in both human and mouse skin. HABP staining of the epidermis and dermis were comparable in human skin but failed to stain the vital epidermis of mouse skin. In human skin, Pep-1 stained the basal, spinous, and granular layers, whereas HABP failed to stain the basal layer. Precipitation of HA in situ resulted in dermal staining but weak staining in the epidermis for HABP and Pep-1. Our results may suggest that Pep-1 is sensitive to HA conformation. Furthermore, Pep-1 may represent a new probe to study HA expression in the skin.
Identification of Adrenomedullin in Avian Type II Pneumocytes: Increased Expression after Exposure to Air Pollutants
Authors: Cuesta Natalia , Martínez Alfredo , Cuttitta Frank , Zudaire Enrique
Published: May 2005

Adrenomedullin (AM) is a potent vasodilator peptide present in the lung of mammals where it is expressed mainly in the columnar epithelium and alveolar macrophages. AM increases the secretion of phosphatidylcholine by type II pneumocytes, which suggests a role as an autocrine modulator of surfactant secretion. In this study we show the expression of an AM-like protein in the lung of the pigeon, Columba livia. Using an antibody against its human ortholog, AM-like immunoreactivity was found to be associated with membranous structures of the multivesicular bodies of type II pneumocytes. We also studied the differential expression of AM-like peptide in the lung of pigeons exposed to polluted city air vs cleaner countryside conditions and found that AM-like expression was higher in city animals. Similar results were obtained in an experimental study in which pigeons were exposed to increasing concentrations of a single pollutant, ozone. Taken together, our findings support the implication of AM in the response of type II pneumocytes to air pollutants.
The Macrophage-derived Lectin, MNCF, Activates Neutrophil Migration through a Pertussis Toxin-sensitive Pathway
Authors: Moreno Andréa N. , Pereira-da-Silva Gabriela , Oliver Constance , Jamur Maria Célia , Panunto-Castelo Ademilson , Roque-Barreira Maria Cristina
Published: May 2005

The macrophage-derived neutrophil chemotactic factor (MNCF) is a d-galactose-binding lectin that induces neutrophil migration in vitro and in vivo. Neutrophil recruitment induced by MNCF is resistant to glucocorticoid treatment and is inhibited by the lectin-specific sugar, d-galactose. In the present study, we characterized the binding of MNCF to neutrophils and the responses triggered by this binding. Exposure to MNCF resulted in cell polarization, formation of a lamellipodium, and deep ruffles on the cell surface. By confocal microscopy, we observed that MNCF was evenly distributed on the cell surface after 30 min of incubation. The labeling intensity progressively diminished with longer incubations. Internalization kinetics showed that MNCF/ligand complexes were rapidly internalized, reaching maximum intracellular concentrations at 120 min and then decreased thereafter. The binding and internalization of MNCF were selectively inhibited by d-galactose. MNCF-induced neutrophil chemotaxis was inhibited by pertussis toxin. This fact strongly suggests that the MNCF-ligand on the neutrophil surface is a G-protein-coupled receptor (GPCR), similar to receptors for well-established neutrophil attractants. Our observations on the ability of MNCF to activate neutrophils are consistent with the increasing evidence for the participation of animal lectins in the innate immune response.
Mosquito Phenoloxidase and Defensin Colocalize in Melanization Innate Immune Responses
Authors: Hillyer Julián F. , Christensen Bruce M.
Published: May 2005

Mosquitoes mount strong humoral and cellular immune responses against foreign organisms. Two components of the mosquito immune response that have received much attention are the phenoloxidase cascade that leads to melanization and antimicrobial peptides. The purpose of the current study was to use immunocytochemistry and transmission electron microscopy to identify the location of the melanization rate-limiting enzyme phenoloxidase and the antimicrobial peptide defensin in innate immune reactions against Escherichia coli and Micrococcus luteus by the mosquito Aedes aegypti. Our results show that both phenoloxidase and defensin are present at the sites of melanin biosynthesis in immune reactions against bacteria. Furthermore, both proteins are often present inside the same melanotic capsules. When hemocytes were analyzed, phenoloxidase was present in the cytosol of oenocytoids, but no significant amounts of defensin were detected inside any hemocytes. In summary, these data show that phenoloxidase and defensin colocalize in melanization reactions against bacteria and argue for further studies into the potential role of defensin in phenoloxidase-based melanization innate immune responses in mosquitoes.
Regional-dependent Increase of Sympathetic Innervation in Rat White Adipose Tissue during Prolonged Fasting
Authors: Giordano Antonio , Frontini Andrea , Murano Incoronata , Tonello Cristina , Marino M. Antonella , Carruba Michele O. , Nisoli Enzo , Cinti Saverio
Published: May 2005

White adipose tissue (WAT) is innervated by the sympathetic nervous system. A role for WAT sympathetic noradrenergic nerves in lipid mobilization has been suggested. To gain insight into the involvement of nerve activity in the delipidation process, WAT nerves were investigated in rat retroperitoneal and epididymal depots after prolonged fasting. A significant increase in tyrosine hydroxylase (TH) content was found in epididymal and, especially, retroperitoneal WAT by Western blotting. Accordingly, an increased immunoreactivity for TH was detected by immunohistochemistry in epididymal and, especially, retroperitoneal vascular and parenchymal noradrenergic nerves. Neuropeptide Y (NPY)-containing nerves were found around arteries and in the parenchyma. Double-staining experiments and confocal microscopy showed that most perivascular and some parenchymal noradrenergic nerves also contained NPY. Detection of protein gene product (PGP) 9.5, a general marker of peripheral nerves, by Western blotting and PGP 9.5-TH by double-staining experiments showed significantly increased noradrenergic nerve density in fasted retroperitoneal, but not epididymal depots, suggesting that formation of new nerves takes place in retroperitoneal WAT in fasting conditions. On the whole, these data confirm the important role of sympathetic noradrenergic nerves in WAT lipid mobilization during fasting but also raise questions about the physiological role of regional-dependent nerve adjustments and their functional significance in relation to white adipocyte secretory products.
Region- and Cell-specific Differences in the Distribution of Carbonic Anhydrases II, III, XII, and XIV in the Adult Rat Epididymis
Authors: Hermo Louis , Chong Dennis Lee , Moffatt Pierre , Sly William S. , Waheed Abdul , Smith Charles E.
Published: May 2005

We employed RT-PCR followed by light microscope immunocytochemistry on St. Marie's- and Bouin's-fixed tissues to define the distribution of carbonic anhydrase (CA) isoforms in the male reproductive tract. The data revealed that CA II, III, IV, XII, and XIV were expressed in rat epididymis. Whereas CA III was found in principal cells of all epididymal regions, CA II was localized in narrow cells of the initial segment and principal cells of all regions. CA XII expression was most intense in the corpus and proximal cauda regions, where it appeared over the basolateral plasma membranes of principal cells. Narrow cells of the initial segment also revealed intense reactions, as did basal cells of the corpus and proximal cauda regions. Principal cells of the initial segment and proximal caput regions showed diffuse apical cytosolic reactions and occasional basolateral staining for CA XIV, whereas principal cells of distal regions showed more diffuse cytosolic reactions highlighting both apical and basal regions of the cell, with basal cells also being reactive. These data suggest subtle differences in cell type and subcellular- and region-specific distributions for CAs in their role of fine-tuning pH in the lumen, cell cytosol, and intervening intercellular spaces of the epididymis.
Quantifying Estrogen and Progesterone Receptor Expression in Breast Cancer by Digital Imaging
Authors: Szeszel Monika K. , Crisman Cameron L. , Crow Lauren , McMullen Steven , Major Jacqueline M. , Natarajan Loki , Saquib Abu , Feramisco James R. , Wasserman Linda M.
Published: May 2005

Developments in digital imaging and fluorescent microscopy provide a new method and opportunities for quantification of protein expression in human tissue. Archived collections of paraffin-embedded tumors can be used to study the relationship between quantitative differences in protein expression in tumors and patient outcome. In this report we describe the use of a DeltaVision Restoration deconvolution microscope, combined with fluorescent immunohistochemistry, to obtain reproducible and quantitative estimates of protein expression in a formalin-fixed paraffin-embedded tissue. As proof of principle, we used antibodies to the estrogen and progesterone receptors in a hormone receptor–positive breast cancer specimen. We provide guidelines for control of day-to-day variability in camera and microscope performance to ensure that image acquisition leads to reproducible quantitative estimates of protein expression. We show that background autofluorescence related to formalin fixation can be controlled and that for proteins that are expressed in nearly every cell, multiplexing two primary antibodies on the same slide does not significantly affect the results obtained. We demonstrate that for proteins whose expression varies markedly from cell to cell, data reproducibility, as assessed by imaging successive tissue sections, is more difficult to determine.
Immunohistochemical Detection of the β4 Integrin Subunit in Pancreatic Adenocarcinoma
Authors: Gleason Brianna , Adley Brian , Rao M. Sambasiva , Diaz Leslie K.
Published: May 2005

The expression of the β4 integrin subunit protein in pancreatic cancer was investigated using routine immunohistochemical methods on paraffin-embedded archival material. Forty-eight cases of pancreatic ductal adenocarcinoma were immunostained with a monoclonal antibody to the β4 integrin subunit, and the extent of staining was compared with that seen in non-cancerous pancreatic tissues, including 15 separate cases of chronic pancreatitis and 6 sections from normal pancreas. We found that the β4 integrin subunit protein was overexpressed in the majority of pancreatic carcinoma cases tested, whereas chronic pancreatitis and normal pancreas did not display substantial levels of expression.
Co-accumulation of Dendritic Cells and Natural Killer T Cells within Rupture-prone Regions in Human Atherosclerotic Plaques
Authors: Bobryshev Yuri V. , Lord Reginald S.A.
Published: May 2005

We previously reported that CD1d, a molecule responsible for the presentation of lipid antigens, is expressed in atherosclerotic lesions and that its expression is restricted to dendritic cells. Recent studies demonstrating that CD1d-restricted natural killer T (NKT) cells are involved in atherogenesis prompted the present study investigating whether NKT cells are present in human atherosclerotic lesions and, if so, whether there is an association between NKT cells and dendritic cells. We found that NKT cells do accumulate in rupture-prone shoulders of atherosclerotic plaques and observed direct contacts of dendritic cells with NKT cells in rupture-prone regions of plaque.
Microdissection-derived Murine Mcb Probes from Somatic Cell Hybrids
Authors: Trifonov Vladimir , Karst Constanze , Claussen Uwe , Mrasek Kristin , Michel Susanne , Avner Philip , Liehr Thomas
Published: May 2005

The multicolor-banding (mcb) technique is a fluorescence in situ hybridization (FISH)-banding approach, which is based on region-specific microdissection libraries producing changing fluorescence intensity ratios along the chromosomes. The latter are used to assign different pseudocolors to specific chromosomal regions. Here we present the first three available mcb-probe sets for the Mus musculus chromosomes 3, 6, and 18. In the present work, the creation of the microdissection libraries was done for the first time on mouse/human somatic cell hybrids. During creation of the mcb-probes, the latter enabled an unambiguous identification of the, otherwise in GTG-banding, hardly distinguishable murine chromosomes.
Intracellular Localization of Oxidized Low-density Lipoproteins in Atherosclerotic Plaque Cells Revealed by Electron Microscopy Combined with Laser Capture Microdissection
Authors: Bobryshev Yuri V.
Published: May 2005

Recently, laser capture microdissection (LCM) has become a powerful tool for investigating the genome and protein contents of cells populating normal and pathologically altered tissues. The present work reports a technique for the preparation of tissue specimens for further LCM combined with electron microscopy. In this work, atherosclerotic plaque cells containing oxidized low-density lipoproteins (LDL) were microdissected from human carotid arteries and the intracellular distribution of oxidized LDL was examined, providing novel information about the association of microvesicles containing oxidized LDL with “lipid droplets” in macrophage foam cells.
Expression of Nkx6 Genes in the Hindbrain and Gut of the Developing Mouse
Authors: Nelson Shelley B. , Janiesch Christoph , Sander Maike
Published: May 2005

The Nkx6 gene family of homeodomain transcription factors consists of three members. For two, Nkx6.1 and Nkx6.2, important developmental roles in the central nervous system and pancreas have been demonstrated. Here we introduce the third member of the Nkx6 gene family, Nkx6.3, and identify similar and distinct patterns of expression for all three Nkx6 genes in the hindbrain and gut of the developing mouse embryo.
Thermal Stability of Wood‐Wood and Wood‐FRP Bonding with Polyurethane and Epoxy Adhesives
Authors: Richter K. , Steiger R.
Published: May 2005

The performance of PUR and EP adhesives in wood bonds at increased temperatures is discussed. DTMA and mechanical tests show that glue‐line thickness and adhesive formulation are decisive for PUR‐bond safety, confirming that any application must be restricted to close contact joints. EP adhesives show strength reductions at temperatures above 60 °C. Up to this temperature high viscous adhesives/modifications perform better than low viscous products. As for PUR, only some products had sufficient strength and stiffness above 70 °C. Best‐adapted adhesives for a specific application must be selected in function of the expected temperature range in service.
Stain Repellent Finishing on Fabrics
Authors: Hegemann D.
Published: May 2005

Stain repellent textiles are still a strong demand from textile industry as well as customers. Therefore, this work deals with an improved oleophobic treatment of PET textiles. Two polyester fabrics with different textile structures were examined, which requires a plasma treatment such as Ar/O2 mixture enabling a good penetration into the textile structure. Using plasma activation prior to the wet‐chemical treatment the oil repellency grade is enhanced by at least one grade.
Dielectric Elastomers in Actuator Technology
Authors: Löwe C. , Zhang X. , Kovacs G.
Published: May 2005

Electroactive polymers (EAPs) are characterized by their ability to respond to external electric stimulation by displaying a significant shape or size displacement. Actuators, based on dielectric elastomers exhibiting low elastic stiffness and high dielectric constants, can produce high strain levels from 10 to 380 %. Typically, acrylic and silicone materials are used as dielectric layer in such actuators. Their potential to mimic the movement of animals, insects and even human body parts are increasingly of interest for researchers in the field of biomimetics, as well as more classical application fields like robotics. The control of the most important material properties, elastic moduli and dielectric constants of the dielectric elastomers and electrode materials, together with the control of fabrication parameters i.e. film thickness, electrode manufacturing as well as design of the actuator configuration allow the fabrication of tailor‐made actuators, which match the necessary requirements for a given application. Theoretical models contribute to a deeper understanding of EAP actuators and improve design and optimisation.
Enzymatic Baeyer–Villiger Oxidation of Benzaldehydes
Authors: Moonen Mariëlle J. H. , Westphal Adrie H. , Rietjens Ivonne M. C. M. , van Berkel Willem J. H.
Published: June 2005

The selectivity of the chemical Baeyer–Villiger oxidation of benzaldehydes depends on steric and electronic factors, the type of oxidizing agent and the reaction conditions. Here we report on the enzymatic Baeyer–Villiger oxidation of fluorobenzaldehydes as catalyzed by the flavoprotein 4‐hydroxyacetophenone monooxygenase (HAPMO). HAPMO was most active with 4‐amino‐ and 4‐hydroxybenzaldehydes. With these compounds significant substrate inhibition occurred. Monofluoro‐ and difluorobenzaldehydes were readily oxidized by HAPMO without substrate inhibition. 19F NMR analysis revealed that 4‐fluoro‐, 2,6‐difluoro‐, 3,4‐difluoro‐, 2‐fluoro‐4‐hydroxy‐ and 3‐fluoro‐4‐hydroxybenzaldehyde were quantitatively converted by HAPMO to the corresponding fluorophenyl formates. These products spontaneously hydrolyzed to fluorophenols. The HAPMO‐mediated conversion of 2‐fluoro‐, 3‐fluoro‐, 2,3‐difluoro‐ and 2,4‐difluorobenzaldehyde yielded, besides fluorophenols, also minor amounts of fluorobenzoic acids. The high preference of HAPMO for the production of fluorophenols is in disagreement with the rule derived from chemical studies that electron‐poor benzaldehydes form mainly benzoic acids. This suggests that interactions of the benzaldehyde substrates with amino acids and/or the flavin cofactor in the enzyme active site influence the selection of the migratory group in favor of the phenyl ring.
Enzymatic Baeyer–Villiger Oxidation of Bicyclic Diketones
Authors: Ottolina Gianluca , de Gonzalo Gonzalo , Carrea Giacomo , Danieli Bruno
Published: June 2005

Cyclohexanone monooxygenase from Acinetobacter calcoaceticus was employed for the Baeyer–Villiger oxidation of racemic bicyclic diketones such as the Wieland–Miescher and the Hajos–Parrish diketones and of some of their derivatives. The corresponding lactones were produced in a highly regio‐ and enantioselective manner. The reactions were carried out using a crude enzyme preparation in aqueous buffer, at room temperature, and the recycling of the expensive coenzyme NADPH was conducted with a second ancillary enzymatic system. The enzymatic process was simple and easy to handle, thus providing a very practical tool to access enantiopure lactones.
Optimisation of the Enantioselective Synthesis of Cyanohydrin Esters
Authors: Veum Lars , Kanerva Liisa T. , Halling Peter J. , Maschmeyer Thomas , Hanefeld Ulf
Published: June 2005

The base‐ and lipase‐catalysed enantioselective synthesis of cyanohydrin esters was investigated, and the problem of previously reported low yields due to residual water in the reaction mixture was addressed. When the lipase was immobilised on Celite R‐633 as a carrier, both the enantioselectivity and the reaction times for this dynamic kinetic resolution were improved, thus enabling a highly enantioselective synthesis of aromatic and heteroaromatic cyanohydrin acetates.
Biocatalytic Asymmetric Dihydroxylation of Conjugated Mono‐ and Poly‐alkenes to Yield Enantiopure Cyclic cis‐Diols
Authors: Boyd Derek R. , Sharma Narain D. , Bowers Nigel I. , Brannigan Ian N. , Groocock Melanie R. , Malone John F. , McConville Gareth , Allen Christopher C. R.
Published: June 2005

Dioxygenase‐catalysed asymmetric dihydroxylation, of a series of conjugated monoalkenes and polyenes, was found to yield the corresponding monols and 1,2‐dihydrodiols. The diol metabolites were obtained from monosubstituted, gem‐disubstituted, cis‐disubstituted, and trisubstituted alkene substrates, using whole cells of Pseudomonas putida strains containing toluene and naphthalene dioxygenases. Dioxygenase selection and alkene type were established as important factors, in the preference for dioxygenase‐catalysed 1,2‐dihydroxylation of conjugated alkene or arene groups, and monohydroxylation at benzylic or allylic centres. Competition from allylic hydroxylation of methyl groups was observed only when naphthalene dioxygenase was used as biocatalyst. The structures, enantiomeric excess values and absolute configurations of the bioproducts, were determined by a combination of stereochemical correlation, spectroscopy (NMR and CD) and X‐ray diffraction methods. cis‐1,2‐Diol metabolites from arenes, cyclic alkenes and dienes were generally observed to be enantiopure (>98% ee), while 1,2‐diols from acyclic alkenes had lower enantiomeric excess values (<88% ee). The enantiopure cis‐diol metabolite of a gem‐disubstituted fulvene was used as precursor in a new chemoenzymatic route to a novel C2‐symmetrical ketone.
Chemoenzymatic Route to Both Enantiomers of a 1‐Isopropyl‐3a‐methyloctahydroinden‐4‐one Derivative: A Synthetic Intermediate for Sesqui‐ and Diterpenoids
Authors: Fujieda Shigeo , Tomita Mina , Fuhshuku Ken‐ichi , Ohba Shigeru , Nishiyama Shigeru , Sugai Takeshi
Published: June 2005

On the way to a chemoenzymatic synthesis of a key intermediate for sesquiterpenoids and diterpenoids, 2‐methyl‐2‐(4‐methyl‐3‐oxopentyl)‐1,3‐cyclohexanedione was reduced with the whole cells of yeast biocatalysts. Torulaspora delbrueckii NBRC10921 reduced a cyclic ketone of three carbonyl groups in an enantiofacially selective manner (re‐face attack), but there was poor enantiotopic group selectivity between two carbonyl groups on the cyclohexane ring to yield a mixture of diastereomeric products. Candida floricola IAM13115 reduced mainly the pro‐(R) carbonyl group. In contrast, the reduction proceeded in an enantiofacially poorly selective manner to give another set of diastereomeric products. In both cases, another carbonyl group on the side chain worked as a ‘trapping arm’ of the resulting secondary alcohol. The diastereomeric products were effectively separated as the ‘syn’ or ‘cis’ isomer exclusively exist in the intramolecular hemiacetal structure, while ‘anti’ or ‘trans’ isomer being an equilibrated mixture of cyclic hemiacetal and open‐chain hydroxyketone (ca. 0.7 : 1). Starting separately from the enantiomerically enriched products as above, both enantiomers of the target compound, a key intermediate for terpenoids, were efficiently prepared via stereoselective ring closure under pinacol coupling reaction conditions. Furthermore, a daucane sesquiterpene intermediate, a hydroazulene derivative, was provided after one‐carbon homologation of the six‐membered ring.
Penicillin G Amidase‐Catalysed Hydrolysis of Phenylacetic Hydrazides on a Solid Phase: A New Route to Enzyme‐Cleavable Linkers
Authors: Basso Alessandra , Ebert Cynthia , Gardossi Lucia , Linda Paolo , Tran Phuong Thao , Zhu Mingzhao , Wessjohann Ludger
Published: June 2005

A novel catalytic property of penicillin G amidase (PGA) is described. Unexpectedly, the enzyme can hydrolyse hydrazide bonds with good efficiency, and in solution the enzyme shows a selectivity that is similar to phenylacetamides. The hydrolysis of phenylacetic hydrazides releases hydrazine, but no inhibition due to the formation of such reactive compounds was observed. This novel catalytic property was assayed also on a solid phase as a pioneering route for the design of enzyme‐cleavable linkers and masked scavengers for ketones. On a solid phase a phenylacetic hydrazide compound was chemically synthesised on PEGA1900 and PEGA+ (two co‐polymers of acrylamide and ethylene glycol) and the efficiency of PGA in the release of phenylacetic acid depended on the diffusion of the protein inside the polymer. On PEGA+ the enzyme, as previously described, shows a good diffusion due to an improved electrostatic interaction with PGA thus achieving good hydrolytic conversions.
Production of Acrylamide using Alginate‐Immobilized E. coli Expressing Comamonas testosteroni 5‐MGAM‐4D Nitrile Hydratase
Authors: Mersinger Lawrence J. , Hann Eugenia C. , Cooling Frederick B. , Gavagan John E. , Ben‐Bassat Arie , Wu Shijun , Petrillo Kelly L. , Payne Mark S. , DiCosimo Robert
Published: June 2005

A thermally‐stable nitrile hydratase produced by Comamonas testosteroni 5‐MGAM‐4D has been expressed in Escherichia coli, and the alginate‐immobilized transformant evaluated as catalyst for the conversion of acrylonitrile to acrylamide. In batch reactions with catalyst recycle, the catalyst productivity decreased with increasing acrylonitrile concentration or reaction temperature, but was relatively insensitive to acrylamide concentration. A total of 206 consecutive batch reactions with catalyst recycle were run at 5 °C and produced 1035 g acrylamide/g dry cell weight and 95 g acrylamide/L; the initial and final volumetric productivities of this series of recycle reactions were 197 and 96 g acrylamide/L/h, respectively. A packed column reactor yielded lower catalyst productivity than consecutive batch recycle reactions, presumably due to contact of the fixed‐bed catalyst with a constant high concentration of acrylonitrile.
Combined Application of Galactose Oxidase and β‐N‐Acetylhexosaminidase in the Synthesis of Complex Immunoactive N‐Acetyl‐D‐galactosaminides
Authors: Fialová Pavla , Namdjou Darius‐Jean , Ettrich Rüdiger , Přikrylová Věra , Rauvolfová Jana , Křenek Karel , Kuzma Marek , Elling Lothar , Bezouška Karel , Křen Vladimír
Published: June 2005

A high‐yield preparatory procedure for the synthesis of p‐nitrophenyl 2‐acetamido‐2‐deoxy‐β‐D‐galacto‐hexodialdo‐1,5‐pyranoside (2) using the galactose oxidase from Dactylium dendroides in a batch reactor was developed. Enzymatic recognition of this aldehyde and the respective uronic acid 3 obtained by NaClO2 oxidation was studied using a set of 36 fungal β‐N‐acetylhexosaminidases from Acremonium, Aspergillus, Penicillium and Talaromyces genera. The aldehyde 2 was readily hydrolysed by all tested β‐N‐acetylhexosaminidases but neither the uronic acid 3 nor its methyl ester 4 were accepted. Molecular modelling with docking into the active centre of the β‐N‐acetylhexosaminidase from Aspergillus oryzae revealed that the aldehyde 2 is processed as a C‐6 geminal diol by the enzyme. The aldehyde 2 was tested for transglycosylation reactions using GlcNAc as an acceptor. The β‐N‐acetylhexosaminidase from Talaromyces flavus gave the best yields (37%) of the transglycosylation product 2‐acetamido‐2‐deoxy‐β‐D‐ galacto‐hexodialdo‐1,5‐pyranosyl‐(1→4)‐2‐acetamido‐ 2‐deoxy‐D‐glucopyranose, which was oxidised in situ to yield the final product 2‐acetamido‐2‐deoxy‐β‐D‐galactopyranosyluronic acid‐(1→4)‐2‐acetamido‐2‐deoxy‐D‐glucopyranose (6). Compounds 3 and 6 were shown to be high‐affinity ligands for two natural killer cell activation receptors, NKR‐P1A and CD69. For the latter receptor they turned out to be among the best ligands described so far. This increase was obviously due to the presence of a carboxy moiety.
Immobilization of Penicillin G Acylase: The Key to Optimum Performance
Authors: Kallenberg Agnes I. , van Rantwijk Fred , Sheldon Roger A.
Published: June 2005

Penicillin G acylase is a major industrial biocatalyst that is used in the enzymatic production of 20,000 t a−1 of 6‐aminopenicillanic acid, the industrial β‐lactam intermediate, as well as in the enzymatic production of semi‐synthetic β‐lactam antibiotics. Because efficient recovery and reuse of the biocatalyst is a prerequisite for a viable process, much attention has been focused on the immobilization of penicillin G acylase. Methods that have been studied and will be discussed in this review include covalent attachment to porous organic and inorganic carriers, inclusion in and attachment to biopolymer gels and carrier‐free immobilization techniques. Highly active and stable preparations have been developed; mass transfer limitations in the carrier are now a major barrier to further improvement of the biocatalyst performance.
Significant and Unexpected Solvent Influence on the Selectivity of Laccase‐Catalyzed Coupling of Tetrahydro‐2‐naphthol Derivatives
Authors: Intra Annalisa , Nicotra Silvia , Riva Sergio , Danieli Bruno
Published: June 2005

The relative ratio of the dimers obtained by laccase‐catalyzed oxidation of tetrahydronaphthyl derivatives was profoundly influenced by the nature of the organic solvent used. For instance, in the oxidation of 5,6,7,8‐tetrahydronaphtalen‐2‐ol (1), the formation of the symmetrical 1,1′ product 1a with respect to the 1,3′ dimer 1b was highly favored in the aromatic solvents benzene and toluene.
Catalytic Hydroxylation in Biphasic Systems using CYP102A1 Mutants
Authors: Maurer Steffen C. , Kühnel Katja , Kaysser Leonard A. , Eiben Sabine , Schmid Rolf D. , Urlacher Vlada B.
Published: June 2005

Cytochrome P450 monooxygenases are biocatalysts that hydroxylate or epoxidise a wide range of hydrophobic organic substrates. Their technical application is, however, limited to a small number of whole‐cell processes. The use of the isolated P450 enzymes is believed to be impractical due to their low stability, stoichiometric need of the expensive cofactor NAD(P)H and low solubility of most substrates in aqueous media. We investigated the behaviour of an isolated bacterial monooxygenase (mutants of CYP102A1) in a biphasic reaction system supported by cofactor recycling with the NADP+‐dependent formate dehydrogenase from Pseudomonas sp 101. Using this experimental set‐up cyclohexane, octane and myristic acid were hydroxylated. To reduce the process costs a novel NADH‐dependent mutant of CYP102A1 was designed. For recycling of NADH an NAD+‐dependent FDH was used. The stability of the monooxygenase mutants under the reaction conditions in the biphasic system was quite high as revealed by total turnover numbers of up to 12,850 in the NADPH‐dependent cyclohexane hydroxylation and up to 30,000 in the NADH‐dependent myristic acid oxidation.
Purification and Cloning of a Ketoreductase used for the Preparation of Chiral Alcohols
Authors: Hanson Ronald L. , Goldberg Steven , Goswami Animesh , Tully Thomas P. , Patel Ramesh N.
Published: June 2005

The synthesis of the leading candidate compound in an anticancer program required (S)‐2‐chloro‐1‐(3‐chlorophenyl)‐ethanol as an intermediate. Other possible candidate compounds used analogues of the S‐alcohol. Of 119 microbial cultures screened for reduction of the corresponding ketone to the S‐alcohol, Hansenula polymorpha ATCC 58401 (73.8% ee) and Rhodococcus globerulus ATCC 21505 (71.8% ee) had the highest enantioselectivity for producing the desired alcohol. A ketoreductase from Hansenula polymorpha, after purification to homogeneity, gave the S‐alcohol with 100% ee. Amino acid sequences from the purified enzyme were used to design PCR primers for cloning the ketoreductase. The cloned ketoreductase required NADP(H), had a subunit molecular weight of 29,220 and a native molecular weight of 88,000. The cloned ketoreductase was expressed in E. coli together with a cloned glucose 6‐phosphate dehydrogenase from Saccharomyces cerevisiae to allow regeneration of the NADPH required by the ketoreductase. An extract of E. coli containing the two recombinant enzymes was used to reduce 2‐chloro‐1‐(3‐chloro‐4‐fluorophenyl)‐ethanone and two related ketones to the corresponding S‐alcohols. Intact E. coli cells provided with glucose were used to prepare (S)‐2‐chloro‐1‐(3‐chloro‐4‐fluorophenyl)‐ethanol in 89% yield with 100% ee.
Biocatalyzed Generation of Molecular Diversity: Selective Modification of the Saponin Asiaticoside
Authors: Monti Daniela , Candido Andrea , Cruz Silva M. Manuel , Křen Vladimir , Riva Sergio , Danieli Bruno
Published: June 2005

An array of different derivatives of the complex ursane‐type triterpene glycoside asiaticoside (1), a saponin component isolated from the perennial herb Centella asiatica, was generated by exploiting the stereo‐, regio‐ and site‐selectivity of four groups of enzymes (glycosidases, glycosyltransferases, lipases and laccases). A library of extracellular α‐L‐rhamnosidases (31 different items) was obtained by screening 16 different fungal strains under different cultivation conditions, and several of these preparations catalyzed the derhamnosylation of asiaticoside. Specifically, the enzymes produced by Fusarium oxysporum were selected for the synthesis of derhamno‐degluco‐asiaticoside (2) and also of derhamno‐asiaticoside (3), by in situ glucose‐inhibition of contaminating β‐D‐glucosidases. β‐1,4‐Galactosyltransferase from bovine milk was subsequently used for the galactosylation of the two asiaticoside derivatives 2 and 3, using 20% v/v DMSO as a cosolvent in order to increase substrate solubility. Finally, new acylated and oxidized derivatives of asiaticoside were also prepared by exploiting the lipase from Candida antarctica (Novozym 435) and the laccase from Trametes pubescens, respectively.
Microbiological Transformations 60. Enantioconvergent Baeyer–Villiger Oxidation via a Combined Whole Cells and Ionic Exchange Resin‐Catalysed Dynamic Kinetic Resolution Process
Authors: Gutiérrez Maria‐Concepción , Furstoss Roland , Alphand Véronique
Published: June 2005

A dynamic kinetic resolution process was applied to an enantioconvergent microbial Baeyer–Villiger oxidation of benzyloxycyclopentanone, rac‐1. This was achieved by combining a whole cell‐based kinetic resolution and an anion exchange resin‐catalysed in situ racemisation. Several resins were screened according to their capacity to catalyse the racemisation of 1. As compared to our previous results, the presence of weakly basic Lewatit MP62 in biotransformations of 1 allowed a three‐fold improvement of usable substrate concentration and afforded nearly enantiopure lactone (R)‐2 (97% ee) in preparative (isolated) yields higher than 84%. Noyori's model was applied to this reaction and allowed kinetic constants determination.
Room Temperature Ionic Liquids in the Kinetic Resolution of Adrenaline‐Type Aminoethanols by Burkholderia cepacia Lipase under Normal and Microwave Conditions
Authors: Lundell Katri , Kurki Toni , Lindroos Maria , Kanerva Liisa T.
Published: June 2005

The lipase PS‐C II (lipase from Burkholderia cepacia immobilized on ceramic particles)‐catalyzed acylations of N‐acylated 2‐amino‐1‐phenylethanol (rac‐1) and N‐acylated norphenylephrine (rac‐2) have been studied in imidazolium‐ and pyridinium‐based ionic liquids, in tert‐butyl methyl ether (TBME) and in their mixtures. Enzymatic chemo‐ and enantioselectivities in the presence of hydrophobic EMIM⋅NTf2 and hydrophilic EMIM⋅BF4 have been studied in more detail using high substrate concentrations. The preparative‐scale kinetic resolution of rac‐1 and rac‐2 (both 0.45 M) with vinyl butanoate in the mixture of EMIM⋅NTf2 with TBME (2 : 1) took 9 and 27 hours, respectively. Microwave‐assisted acylation of rac‐1 and rac‐2 in the presence of EMIM⋅NTf2 proceeded similarly to the reactions under normal conditions.